I've used Prepware Remote Pilot for both my initial and recurrent Part 107 tests. It is really nice and only costs a few bucks, if I remember correctly I got a 95% on the recurrent test. You can get it on Google Play HERE and on iOS HERE
If you do nothing else, buy yourself a copy of the Sectional Chart that covers the area nearest where you live - and STUDY IT intensively - even when you are waiting for a pizza, a haircut, or just looking for something to do in the evening. Study it instead of watching TV, because you can expect 5 to 10 questions about what information the chart tells you.
GREAT advice!! I have a whole fleet of sUAS/Drones and only about 1/3 of them are MultiRotors (I have quads and Hex).
Some people feel like the questions aren't fair because they talk about things like weight & balance, airport traffic patterns etc and these don't apply to them. But every remotely piloted aircraft under 55lbs and not flown by the military fits into this classification regardless if it's a heli, airplane, or mutilrotor. Just because you or I may not be exercising the full scope of the test, others in the country are doing those exact things and it should be a part of the test.
Look for Tony Northrup in YOUTUBE. He has a video on the test and some nice work on drones in general. I read a book or to and then took a 1 day workshop at the photography event in Dallas and took the test the next day. Different perspectives help a lot.