Here are some techinques that aren't in the manual or are hard to learn.
One-shot missiles: Hold down the Y button and select missiles, super missiles, or power bomb. Instead of being normal green it will flash. Once you shoot one shot it will go back to normal. This is usefull when you want to use only one missile or whatever, but I find it quicker to just hit Y after using the weapon.
Power ball: Run with speed booster then jump diagnolly (don't fly). Crouch in mid air then turn into a ball right before hitting the ground. You can destroy certain rocks with this, but you need a wide open space and have to hit level ground. The timing is really critical and it's really hard to get. You can destroy some blocks below you ship but I haven't found any pratical use for this.
Using Reserve Tanks: To recharge energy from the reserve tanks manually, change the mode to manual, and move the cursor down one step next to reserve tank. Then press fire to use that energy.
Restore Energy (it's called Crystal Flash in Player's guide): This is shown in the intro. You must have less than 50 health (including reserve tanks), altleast 10 missiles, atleast 10 super missiles, and atleast 11 power bombs. Go into a ball and hold L, R, and down. Then use a super bomb and keep holding all buttons (including the fire button). You'll know when to let go. I find this some what use full, but the effects are what's really worth it.
Wall Jump (Wall Climbing, Triangle Jumping): As the etecoons (the little gremlin guys) try to show you in Brinstar, you can jump back and forth between walls to get up long vertical shafts. Just jump towards a wall and make sure you are spinning. Just after you hit the wall, push towards the opposite direction and press jump. It can be hard to keep going, but it can be done infinitely if your timing is right (and there's room above where the etecoons are). It is also possible to do this off of a single wall by jumping out and back, but this is very difficult.
Charge beam used as screw attack: Hold the fire button then do spin jump through an enemey while still holding the fire button and it will hurt them but it doesn't do much damage.
Speed Jump: If you have the Speed Booster, run fast until you turn blue. Then jumping will hurl you diagonally in a large parabola for a long distance. It only works in large rooms, like in Crateria or Norfair.
Special Attacks: These aren't in the manual or mentioned in the game (except one is shown in the intro). You must have charge beam, atleast one power bomb, and atleast one other beam. Select power bomb, charge beam and ONE other beam. Hold the fire button, it takes a second or two to do it and you don't even have to be crouched down. Here's what each gun does: SPAZER: Several small spazer blasts that fly off in a direction of your choice. ICE: A rotating shield of ice. WAVE: Four purple balls that orbit you and then fly out. PLASMA: Four green balls that orbit you in a circle that get larger and larger.
Power Jump: Dracola (the ostrich) demostrates this in Brinstar. To do this, just run using your super speed. When you start flashing, tap down (crouch). You will then be flashing for a few seconds.
Bomb Spread: charge you weapon and go into a ball (keeping the fire button held). Then let go and 5 bombs will spread around you.
Ball climbing: This is a technique to get you into places that are too high to reach before you are really meant to get there or before you have the right equipment. It is done by rolling into a ball and then placing bombs at just the right times to keep bouncing you higher into the air. It is done easiest by using a rapid-fire control pad, but it can be done if you have good timing. Try to hit the button along with the music in most areas. In most cases, this works fine and it is easy to keep your rhythm. It can also be very time-consuming, so don't use it if you want to see the good ending.
The spin jump is important if you want to start the flight from a slightly different position. This does take away your energy. The amount drained depends on how far you go. Running through a door cancels your super speed, but if you are already in the flashing stage, it will be maintained.
Then:
Do:
To: Tap Jump
Fly straight up Hold R, Tap Jump
Fly diagonally up Hold Left, Tap Jump
Spin jump left (repositioning without flying) Left and Jump
Fly left (timing is critical)