It takes some time to get good at Gambler. If it feels awkward at first, but believe me, it gets better as you learn the skills and specialize your legendary items around it. Here's the scoop.
It is not hard to figure out which traits to load up, and which legacies are useful.
Legacies (for weapon or bag):
You want Gamble Chance and Lucky Strike CD obvioulsy. Bleed Legacy is also useful. Also think about the Clever Retort Legacy (CR is available with 5 Gambler + capstone iirc without being in mischief)
I always have Addle CD. Other generic for any burg: Crit Response, Sneak Speed, Positional