Jelly Defense Hints for iPhone/iPad
Don't use your power-ups straight away, it is best to save them for emergencies like when you're just about to lose your gems.
The blue-and-red units during the early stages of the game can be incredibly useful. Try and place as many as you can afford before moving onto single-coloured units.
There is a shortage of Gold coins and they are an important resource in the game so it is advised that you use them frugally when you have them and upgrade your jelly towers by killing jelly monsters.