-The image has you smiling
-The image is not obscured or blurry
If you get to upload multiple pictures, try to make sure:
-The pictures show you engaging in your hobbies and out with friends
-The pictures show you with pets if you have any
-The pictures show you on vacation having fun
The goal is to show as much of your personality in your photos as possible. This will decrease the odds that potential matches swipe past you.
Tip #2: Make sure you fill out the whole profile.
Take advantage of all the fields and features you have access to.
If you can upload up to 10 photos, then do so. If you can verify your photos or personal information to unlock new features, do that. If you can upload a video message or a voice caption, do so.
This demonstrates you are thorough and willing to put in the effort. This will significantly increase the number of matches you will get compared to doing the bare minimum.