Dylan, this is what I'm proposing
You can choose to win whatever category you like today. But if you're going against me it will take $12, if you're going against everyone else it will take $9. If you take the 10 points, you know you can win that with $9 and I have no incentive to try to mess with you, because I'm getting more points another way. So you can put the rest to trying to win a lower category. You don't really have much chance of getting 5 points, but I think you can get more than 0 points that way. I cannot. If you go for the 15 points, I have incentive to try to mess with you, so you really need to commit enough money there to block me. Which means you probably can't win a lower bid. 15 is still more than 12 or whatever, but not my as much as it's worth to me to try.
So here's the deal:
A) You cooperate with my plan, which works out better for the 2 of us as a 2-person group. I owe you one, and in the next couple of games, I try to find some little thing or things I can do to help you out, like I was talking about earlier.
B) You announce in thread that you are taking 15 points and I can go to hell. You probably win the 15 points, unless you try to get cute and underbid. Next turn, I do my best to block you out of any points, but after I've done one thing that hurts you, I consider us even and move on.
C) You claim you're going to go to do one thing and do the other to cost me more points. In devote at least the next 3 rounds to trying to mess with you.
This accomplishes my other goal no matter what, which is to establish a precedent of following through on promises. No matter what you do, I'm making a promise, and I'll follow through on that, which has value in itself in the long run.
Anyway, let's be friends, not enemies.