The Crate Maze

Crates:

Metal Crate:
Challenges: None, really. Its pretty darn challenging to get through them; they're generic impenetrable objects. Used for blocking the path and creating level structure.
Advice: Uh...ignore them. They are like mountains: Maybe someday you will conquer them, but for now, they are just a part of the scenery.

Wooden Crate:
Challenges: Once again, its hard to develop challenges based around something so easily removed. Mostly you just chop these to pieces and be done with it.
Advice: Be wary of these. They can be misleading. You may not need to remove them from your path to reach the finish square.

Vine Crate:
Challenges: Challenges based on the Vine Crate are usually simple: they restrict multiple areas, but only one is useful or there is an order in which they should be removed.
Advice: Always look behind them before you burn them. You want to know what you're getting from burning your bridges (ahaha). If there's fire back there, go for it. If there's not, think carefully how you are going to remove other Vine Crates or weather you need to.

Stone Crate:
Challenges: Most of these are standard RPG fare: put the block in the right place/get them out of your way/use them to depress switches. They are also often used to restrict access to other areas (kind of like one-way passages that show up in Victory Road so often). A bunch of challenges also involve correct positioning for Ice Crates.
Advice: Think before you push. If you're going to trap a block against a wall or in a corner, make sure you are doing it for a reason. When Ice Crates are involved, you can position them to change the stopping points for the Ice Crates.

Ice Crate:
Challenges: Another classing for RPGs. These slippery blocks travel straight until they hit something, so most challenges involve moving obstacles out of/into the way to change where the blocks slide. There are also some challenges where you need to drop ice into lava. Pick the right place to freeze over.
Advice: Again, think before you push. Its very easy to trap your Ice Crates places you don't want them. A good idea would be to plot out your path from origin to switch or lava. Make sure everything is set up correctly before you being pushing--one wrong move and you could find your self trapped behind an Ice Crate that has gotten stuck on a Vince Crate or Wooden Crate you forgot to remove.

Locked Crate:
Challenges: These blocks are very Zelda-esque. You need keys to remove them, so you've got to do things to get the keys. Other than that, the only real challenge is deciding which blocks to unlock. Many times, Locked Crates come in sets.
Advice: Don't just recklessly unlock things willy-nilly. Consider the prize behind the lock. Do you need it, or can the key be better used elsewhere? If a set of these appear, make sure you have enough keys to make it all the way through before starting in on the unlocking process.

Magic Crate:
Challenges: Mostly, you have to arrange field objects in the proper way to remove these. Sometimes, you just need to pick up the right item.
Advice: Look around the level--there is almost always some sort of queue outside the area you can walk in as to where your Stone Crates should end up. Usually, things like Vine Crates or Wooden Crates have no bearing on correct alignments; they are merely used to give you some sort of orientation clue, so pay attention. Sometimes, getting rid of Magic Crates can be as simple as completing an obvious puzzle (see the image of Level 11).

Target Crate:
Challenges: This crate does not make an appearance in this game! It's just a placeholder until I can think of a way to use bows and arrows to get things done.
Advice: If you see this crate, you've probably got something screwy going on, so let me know in some sort of bug report.