What wagers should you use?

Of the wagers that I personally know I'd really recommend only 3 wagers, and those are: Unstoppable wager, Battle Victory wager, and Destroy 5 units wager.
Unstoppable: This one is mostly simple, you can just hop on air, pick an strike aircraft for the air spawn, and ground pound for thunderer/antimech.
Battle Victory: Sure you can't really control who wins unless you're goated, but you really have a 50/50 most of the time unless you're just having a bad day. Though a tip is to just go with whatever nation that just dominates at a said br and you should have not much trouble raking in wins.
Destroy 5 units: Either play ground or for air just go arcade, it isn't that hard to get 5 kills on both of those, unless you can't afford crews.

There's really only two: Best Squad, and Kill 10 Units wagers.
Best Squad: You can't really rely on your randomly chosen squadmates, so just squad up with your friends and lock in, or get carried by friends who are actually good at the game. Problem here is I don't have any.
Kill 10 Units: I lack the skill and brains to reach 10 kills in Arcade games every time so yeah, it's a hit or miss at times.

All of the rest.
Wingman: Who the hell goes for assists, like genuinely.
Mission Maker: Not something you can manipulate easily
Wing Breaker: I guess it would be a maybe for ground but I'm an air player, so just don't :)

Yeah that's about it.