This game is really tough, especially with the floaty control scheme, but here are some tips that'll help you get through it.
Get Used to the Controls
The first thing you'll need to do with a game such as this is get used to the control scheme. You hold your finger down on the screen to get Ironpants to fly upward, and remove it to have him fly downward. Don't fly too close to the ground, though, or he'll crash. It's important to find a tapping rhythm that keeps him soaring, but not to the point that you can't quickly change direction to get through the next section of crates.
Stick to the Center of the Screen
When it comes to successfully flying through crates, position yourself in the center of the screen. You can do this by continuously tapping on the screen so that you stay right in the middle. This allows you to quickly adjust to any gaps that appear, though sometimes you're just going to crash. Try to work on your timing and eventually you'll get the hang of the game.
Don't Give Up
Ironpants is one of those games that will just test your patience. You're going to crash like crazy the first three or four (or hundred) times, but that's just part of the learning curve. Just keep up with it and continue to try and score better runs. If you still can't get past the first set, don't get frustrated. You're not alone.
Know When to Take a Break
When it comes to playing a game like Ironpants, you don't want to stick around for prolonged sessions, because chances are you'll become completely frustrated and maybe even damage your smartphone or tablet in the process. Don't be afraid to take breaks every once in a while, calm yourself down and try the game again. In addition, you'll be able to rest up your hand, which will cramp over time with all the screen tapping. Take it easy.
Realize that You're Going to Crash...Often
You need to understand something with Ironpants, and it's the same logic that came with Flappy Bird and Dark Souls - you're not going to succeed very often. This is a game that comes with a heinous learning curve, and even if you think you've gotten the hang of it, you'll crash by the fourth or fifth row of crates. This game will chew you up and spit you out. Persistent gamers will be rewarded. Everyone else...well, maybe you should play some Tetris or something.