Make sure to look for the hidden bonus coins. They can help you to find difficult objects and can give you some more time or even some bonus points.
Save your hint and fast forward coins for when you really need them (the objects are harder to find as the rounds progress). If you don't use them immediately, they are saved for use in future rounds.
You can use the time bonus coins just before you finish to get a higher time bonus, even if you aren't running short of time.
If you like a more relaxed pace of game, try turning on Relaxed mode and you will no longer run out of time.
Try and find objects quickly to earn a quick find bonus.
Match the groups mini-game
Try and create large groups of the same object in order to earn more bonus objects and to get a bigger score.
This mini-game can become hard in the later rounds if you don't plan ahead. The key is to use the bonus objects (the blue or red ones with the arrow shapes) to destroy entire rows of wooden blocks. So plan your moves so that you can create groups of 5 or more objects (that is how you earn bonus objects). Then when you click on these larger groups, make sure you click on one of the objects in the group that is on the row you wish to clear. The bonus will appear on the object you clicked on. If you follow this strategy, you should be able to get through these rounds - but it may still take a few tries.