I'm personally a big fan of not enforcing the monetization. Sure, I'll put in, say, in-app purchasing, but I like to let the player be able to just grind to afford everything in the game if they choose to do it. It'll take a lot of play, but if that's how they want to go, then that's how they can go.
I also like to make video ads optional, but give a reward for watching them. In my most recent game we had it so that they had to collect jigsaw puzzle pieces in the map (they were very easy to find) and at the end of a round they could choose to watch a video to get a currency reward relevant to the number of jigsaw pieces they found. In testing, people have responded well to it, and the video reward system ended up being quite popular as a kind of minigame inofitself.