When you stretch Cyto between two different tufts of grass, be very sparing with the amount you pull him back by.
Stay away from the red coral! The slightest contact will finish off Cyto and you'll have to restart the level.
If a flowing stream stands between Cyto and his target, you'll need to take its effect into account when planning his trajectory.
The memory fragments in the game are used to unlock new sets of levels, but you don't need to grab every last one to complete each stage. If you're really struggling, two will do and concentrate on getting him to the exit point.
You can leapfrog between bubbles by stretching him across two different tufts of vegetation, then popping the tuft you don't want him to remain on.
You can unlock new stage by spending real money in the cash store, or go back to the very early levels in each stage to get all three memory fragments.
Be very careful with the jelly-coated surfaces.
Don't forget that you can detach Cyto from the orb he's attached to by tapping on the orb itself. If you do this, he'll drop cleanly.