Domination victory is always either the easiest or the most difficult victory type, depending on how many people are in the game and how aggressive the rest of them are. Low-level AI like chieftains tend to make for easy pickings. I recommend you play a game with the "aggressive AI" ticked before you play with humans, just to develop a habit of being on guard.
Most people also tend to develop a favorite civ over a couple playthroughs. A couple things to look for are which kind of victory you want most to pursue and which era are you most comfortable in, and then pick the bonuses that coincide with the first with unique units at a tech level that coincides with the second.
There are some people that choose to do the complete opposite - picking bonuses that coincide with what the player struggles with most, but 9 times out of 10 it's better to focus on your strengths.