Hey @angelic1408 --
Welcome to Leap Motion development! Unity is a great place to start. First, I want to direct you to the Getting Started in Unity guides/video tutorials we have on our Developer Portal, in addition to our Examples Gallery.
Due to occlusion, a "thumbs up, thumbs down" trigger gesture might be slightly less reliable than other hand positions. One of our resident UX researchers and software engineers elaborated a bit more about this in this thread here. (Note: despite what the thread says, the newest version of our software is in fact able to detect the difference between each hand and each respective finger.)
You might also find this thread helpful as a quick guide for programming gestures.
With all of this said, we are constantly refining our Unity assets, so please let us know (other than thumbs up and thumbs down) which gestures you'd like to explore for your project.