I'm not very good at games, and my strategies aren't very good... I just try for minimum, for the sake of unlocking information and plot. I'm sure there are MUCH better ideas from better players...however, this is how -I- survive Hell.
The most important thing to do is to take it slow. Speedruns are deceptive, and watching them is a misleading way to learn the stage. The reason the players in those stages can fly past so quickly is because they know the stage like the back of their hand...which is something that comes from taking it slowly many, many, many times beforehand.
One hint I can give for early (when you're NOT going for speed)... is that if you find yourself losing a LOT of HP in the second area (falling blocks)... take the two hearts in the next room, then go BACK to the block room, then drop back down again.. the hearts will refill indefinitely this way, and early on when you're not going for a speed-time, you can use this method to build your health back up. Also, DON'T rush the blockroom... it's actually faster to move through that room slowly and not take as many hits than it is refilling 50-or-so HP on 2HP hearts.
Also, take room 3 slowly, and try to kill -everything- that can be. **And if you have a decent amount of health, don't take any of the hearts lying around. Wait until you're just about to reach Heavy Press... if, by then, you have little HP, go BACK through the stage and pick up the hearts that have been sitting around. That should give you decent HP, if not refilling you completely, before Heavy Press.** Who is best dealt with using level 3 missiles. He'll go down in seconds. Just make sure to jump over the Rollings.
As for Ballos...ehhh.... my strategies don't work for my friends, and theirs don't work for me. o_o
Oh, and make sure you have the Life Pot. The Life Pot is your GOD.
But enough of my generalizations. Here's a good rundown that I used quite a bit:
http://www.livejournal.com/community/doukutsu/7185.html#cutid1
**
Of course, this is actually kind of stupid, but it works for me. Because I can go through area 3 without taking many hits if any at all, but as SOON as I get to that last room before Heavy Press, I somehow end up getting a facefull of spikes and Bute-butt, and lose a LOT of HP. It's inexplicably retarded.