Tilestorm HD Hints for Android
If you get really stuck on a level you can press the timer on the top of the screen to 'Give Up', which will mark the level as done. Remember though that you can only do this 15 times so do it wisely.
There will be times that you will get yourself into a harder position than when you started. If this happens it is often better to just reload the level and start from scratch.
If you are getting bored with a puzzle you can always go and play another level and return refreshed. You don't have to play the levels in order in each section.