Ok I'll do my best to explain it by typing.
So as a DE you have to understand what the offense is trying to do.
Let's take running plays. As a DE (I'm assuming in a 4-3) your main responsibility most of the time will be outside contain. Sometimes outside contain will be on the OLB.
On a sweep coming to your side you're job would be to force the runner back inside so the MLB can make the tackle. But you can't get outside TOO fast cuz you'll end up giving the runner too much room to cut back inside. When watching the runner keep your eyes on his hips. Not his helmet. Not his feet. Not his shoulders. Watch his hips, they'll always tell you where he's going.
One thing before I go on. You'll often hear your coaches tell you to "Keep your head on a swivel". This means you need to NOT get tunnel vision. Use your peripheral vision. Keep your focus on the play, but be aware of what's going on around you, especially in the direction the runner is going. If you end up unblocked, chances are someone is coming to crack down on you. Usually a WR or maybe a TE split out wide or a FB that went in motion.
Back to defending the toss... when the runner is moving outside, don't get ahead of him, try to mirror his OUTSIDE shoulder. YOu want to "invite" him inside, but don't give him too much room. Like I said, he could end up cutting back inside but if you're too wide you'll leave a hole between you and the MLB.
If the OLB has outside contain then either a TE or Tackle will be trying to hook you. That means they'll be trying to keep you from going outside so that the runner will have room to cut back inside. When that happens you basically just want to power the blocker down the line of scrimmage. When the OLB forces the runner inside he'll likely be coming right into you. Try to bully the blocker towards his outside shoulder. If he tries to get by you you've got an easy tackle. If he tries to get inside he'll have less room since you've successfully driven the blocker down the LOS. The MLB will clean up.
If you don't have a TE lined up on you and the tackle ignores you and tries to loop for the OLB (or scoob the MLB) then 1 of two things is going to happen.
1. It's a run to the outside (opposite side as you) or
2. It's a trap play and you'll be having a guard coming right at you. All you can do is get low and try to cause a traffic jam. Get into the guards legs a create a pile. RBs hate piles at or near the line of scrimmage. Make sure you close the gap on the guard before taking on his block though. If you wait for him to come to you there will still be a hole for the RB. Close the Gap and create the pile.
Another possibility is what we used to call a cross block or an axe block. Basically the Tackle blocks down on the DT and the guard (on your side) kicks out. Same rule applies, close the gap, create a pile.
If you're REALLY quick or the trapping guard is slow you could try to make the play yourself. Just remember, watch the runner's hips.
You're 6'5", so make sure your constantly staying low. As a FB I loved blocking tall DE's cuz they always stand up too high. Gives us more area to block. Staying low helps you keep your leverage when you absorb a block as well.
As far as pass rushing goes, the best attributes to have are a quick first 1-3 steps, and good hands. That OL's job when pass blocking is to get their hands on you. Don't let it happen. On pass plays you'll have gap responsibility just like you do on run plays. But you can still attack at angles that will make theTackle think you're coming one way, while you're still controlling whatever gap you're responsible for. Let's say you've got the 8 gap. That means you have to control the outside of the tackles' shoulder. The 0 gap would be wide to the outside.
Real quick... most teams use a number system for gaps. On offense if the play is a "32 Dive" That means the play would be going between teh center and right guard (a running play). Gaps to the right are even numbered, gaps to the left are odd numbered. So the 4 gap would be between teh RG and RT. 6 gap would be right off the RT's shoulder. 8 gap is wider to the right. Some teams even throw in a "0" gap which is way wide right.
1 gap is between the Center and Left guard. 3 gap= left guard/left tackle, etc...
Anyway, when pass rushing if you're the LE and you have 8 gap responsibility then you can't get inside the tackle, but you CAN make him think you're going inside. Reggie White was a master at this. Start off your pass rush attacking the inside shoulder of the tackle, then use your left arm to get the tackles hands off you (preferrably before he locks on) then use your right arm to rip under the tackles outside shoulder. Rip moves are better than swim moves cuz people tend to "stand up" when using a swim move.
You're tall though so it could be hard using a rip move if the tackle is really short. You can use a swim move just make sure to keep your leverage, don't stand straight up.
When pass rushing, don't look at the tackle (or whoever is blocking you). Look THROUGH him to the QB. You need to see what drop he's doing. If he's doing a 3 step drop then the pass is likely going to come out quick. Be ready to get yoru hands up to bat the ball away.
One thing though, when an offense does a 3 step drop (or a 1 step drop) the tackle will almost ALWAYS try to chop block you. They do this to force you to get your hands down to defend yourself. If you're keeping your leverage you can absorb the chop block but still get your hands up in time to possibly bat the ball down.
Mix things up as a pass rusher. Don't ALWAYS fake in then go out when you have outside responsibility. Sometimes go outside when you ahve outside gap, use a bull rush, spin moves, etc...
Oh, this one's important. When closing in on the QB, never "Aim" at him squared up (unless you're gonna blind side him). Attack his throwing arm shoulder. Most QBs, when they get pressured, run to their throwing arm side. For example, a right handed QB will want to run right. Don't aim TOO far outside though cuz if you give them too much room to cut inside you, they will. Best bet is to aim at their throwing side's nipple. If they try to come inside you you'll have enough leverage to still grab him. But even if you do force him to go the other way it's not so bad cuz it's a lot harder to throw the ball behind your body (right hander throwing while running left) then it is to throw to their throwing arm side (right hander throwing while running right).
Also, watch lots of film. Learn the QBs tendencies. Some QB's love to step up in the pocket. If that's the case you'll have to use your bull rush more often.
Other QBs like to take a jump step backwards before scrambling right or left. If that's the case aim a little bit (just a little bit) behind them when you close in on them. It's all about angles. If you aim just a little bit behind them the QB will likely still try his jump back before scrambling. Only you'll have a better angle to still get the sack, plus you know he's gonna try to do that so be ready to burst that direction when he does it.
Study the OL you're facing. An OL will almost ALWAYS tip off whether it's a run or pass, especially at the high school lvl. Watch where the put their hands on run plays/pass plays. See if there's a difference. If they're in a 3 pt stance, look at their knuckles. On running plays they'll usually put more weight on their hands cuz they'll be moving forward. So if you see their knuckles turning white, it's a running play. Watch the tackles feet. Not just before the snap, but right at the snap. If youre the LE and the RT's right foot moves backwards right at the snap, it's probably a pass. You can really gain an edge if you know whether it's a run or pass. Especially if it's a pass.
Also, learn to get off on the snap of the ball. You can have a quick first step, but if you aren't taking off right when the ball is snapped then you lose the advantage of that first step. When you're in your stance, look through the tackle, but use your peripheral vision to see the ball. EXPLODE off the snap. You don't have to be fast to play football. You can make up for any lack of speed by getting off on the snap of the ball. My fastest 40 time ever was a 4.7 but I was extremely quick off the snap. I used to get so focused on the movement of the ball that I'd literally block out all sound. This is also very helpful on FG and Punt blocks. If you get off on the snap and you can shoot through a gap you'll get some blocks.
If you end up playing safety you just have to make sure you've got your main responsibility taken care of at all times. If it's cover 2, you've got deep coverage. Don't get beat deep.
Learn the QB's tendencies. Some QBs will do something right before they throw the ball (ex. Bledsoe always patted the ball right before throwing). Learning those tendencies will help you to jump a lot of routes. That said, a good QB will use that against you if they realize what you're doing. That's rare in high school though.
When it comes to bringing down a runner/reciever, you're main job is to get the tackle, not the big hit. You are the "SAFETY" that means you're almost always the last line of defense. If you miss the tackle, you end up watching Stephen Jackson trotting into the endzone for a 60 yard TD run. Watch the hips. See what you're hitting (that means your facemask goes into the one your tackling, not the top of your head). WRAP UP and bring him down. Sometimes you'll have the opportunity for a big hit. You don't ALWAYS have to take them. If it's 3rd and 10 and they run a quick slant, go for the tackle, not the hit. The tackles forces a 4th down. A hit, they could break the tackle and get the first down.
STUDY the opponents route combinations.
Also, when studying, write down on a piece of paper how many times they do a certain route, and even write what formation they were in when they did it. Teams have "Favorite" plays. Learn them so you can stop them.
Edit: I put more info regarding the DE position for two reasons. 1) I played some DE so I know more about it then Safety and 2) you're built like a DE. You've got room to grow. You can play some TE and DE. Playing both will help you understand each position better.
For example, I played DE in highschool (and semi-pro) and it really helped me out as a FB cuz I understood their responsibilities better. If you know your opponents responsibilities, tendencies, and techniques you can use it against them.
