Some levels have hidden items that can be collected, like special red flowers. Take them since these items go towards levelling-up your dots, so find them whenever you can.
In the ravine area, you may find a stray dot or two off the beaten path that you can take them along for added security.
Keep in mind touch controls work best for levels with narrow paths, and tilt works well on wide-open meadow levels. Change controls according level you play.