Defensive Basketball Tips

So I saw a video on line and while I agree with some of the concepts there are other that I think are wrong.  Defense for basketball is one of the hardest things to get right, but oh what a difference it can make if you understand defense.  For one it is difficult to practice, everyone can dribble and shoot on their own but no one works on defense by themselves.  A lot of times we give credit to people for being "good" defenders when they are simply very active and maybe even fast, but don't necessarily use correct or good technique.  Plus how often do you hear when watching a game that a player is a fantastic positional defender?  Not exactly the flashyist comment is it?  So let's start with the very basics.

BASICS

See the ball - never turn your back to the basketball especially on defense.  good offensive players will take advantage.
Try to keep your back to the basket.
Stay between your person and the basket.
Bend your knees and keep your butt down, hands out when in a stance.
Slide your feet - basically don't cross your feet or a good offensive player will go right by you.

So that is what I try to get my elementary kids to do to start with.   If you master these concepts you at least aren't a space cadet on the defensive end.  So then how do you become a "good" defender?

MODERATE

Talk - always communicate with other players about where the offense is and any screens.
Ball - you - man - This concept keeps you in a position where one - you see the ball and the person you are guarding, and two - you are in a position to defend a pass to your person.
Know personnel - this is a little higher level concept, but if you are guarding a shooter you need to be close to that person if they are away from the basket.  If someone is not a great shooter you don't have to guard them that closely away from the basket.  This will also determine if you need to try and get over screens (good shooter) or can go under a screen (bad shooter).
When trying to block a shot be the second person off the floor.  If you don't do this you will constantly be falling for fakes and be out of position.

HIGHER LEVEL STUFF BUT REALLY SHOULDN'T BE

When guarding a right handed player you should challenge a shot with your left hand.  This is a concept that is lost on players or never taught to them, but makes sooooo much sense.  If you try to block a shot with the right hand on a right handed player, your entire body has to rotate or slide over to where you are no longer if front of the player.  If they faked the ball and you bit on the fake they will be able to go left with very little resistance because you are horribly out of position.  This is why left handed players have an advantage because their instinct is to block the shot with their strong hand and it happens to line up with right handed players, so they are able to stay in front of the offensive player the entire time without getting badly out of position.  Sometimes it is hard to tell if a left handed player is good at defense, because they have a natural advantage.
Never try to steal the ball from a good ball handler when the ball is in their hands.  They are too good at dribbling and by waving your hands your feet will stop moving or you will get off balance and they will expose you.  Be patient against a good ball handle and be content to make them work hard or travel the furthest path to the basket.  "You reach, I teach" is a favorite motto of good ball handlers.
Keep your hands at ball level.  If a player is dribbling you don't have to worry about blocking a shot so your hands shouldn't be up in the air.  You should be worried about them passing the ball, though.  If they are dribbling hands should be out, palms up.  If they have the ball in a triple threat, hands should be out to the side preferably with the hand to guard the shot forward towards the ball handler.  If they raise the ball to shoot or pass, the defenders hands should go up.  If they have already used their dribble, you can move in extremely close so that passing angles are taken away, just don't get beat on a back door or give and go, you still have to stay on balance and in front of the offensive player.
When there is a lot of distance between you and a ball handler you should flatten out.  If you have a shooting hand forward (and by extension a foot forward) a good offensive player will attack the front foot to get you to open your hips.  So if you don't give them a direction they have to pick a direction and you can easily slide over and take a charge if they drive at you.  Ideally by being flat (both feet the same distance from the ball handler) the ball handler will stop their forward progress and you can assume a more natural defensive stance.  If they are still coming at you while flat they will have to take a much wider path in order to make it around you without charging.  At that point you should have help or be able to easily drop back to pick them up. Always start to their strong hand and if you can, keep the ball centered on your body from a position stand point.  This is where quicker defenders have an advantage.
When guarding the ball prior to a dribble keep the foot forward that matches up with their shooting hand.  So for a right handed shooter you want your left foot towards the shooter, but outside of their stance or at least outside the ball.  The reason for this is, if they still try to drive right, they have to go around your foot which will give you a chance to drop your hips and still be in front of them on a drive.  Ideally they will be forced to go left, but if they pull up for a shot you will be directly on their shooting hand.  The key thing here is to not switch which foot is forward with out the ball handler committing to dribbling in that direction on a hard drive.  If they are just sliding right or left you want to slide with them but still in a position to challenge the shooting hand.  Why move your right foot forward to keep someone from going left if they shoot right handed?  They will be able to shoot right over top of you because you aren't in a position to block or challenge the shot effectively.