I didn’t know anything about the rules of playing dominoes and I still may not, given that for all I know Rockstar just made all this up. But if I remember correctly, the version of dominoes you play in camp is Threes, which just means that you want all the open ends of any played dominoes to add to a multiple of three. If they do, you get points. If not, you get none.
So let’s say you get to lay down first. In that case, the best domino to have is the double sixes, because just laying that down gets you 12 points. If you had a domino that was six on one end and five on the other, you’d get no points, because the total of the open ends would be eleven, not a multiple of three. OK, so that’s the easy part. You also want to get rid of your high number dominoes first because any you’re still holding if your opponent goes out gets calculated into their score. So again, laying out the double sixes is a good move if you have it.
Let’s say you don’t start, Tilly does. And she lays down the double sixes, and gets twelve points. Naturally you need a domino with a six on one end just to lay down. If you have a domino with a six and a three, you get nine points. You’ve closed off one end, putting your six end against one six end of her domino. But the open ends are the six of her original domino, and the three of your domino you laid down. That gets you nine points.
Anyway from that point, you just want to try to keep your options open and if possible, lay out all your dominos first, but of course there’s an element of luck in that, so good luck. Hope that helps.