I've only played Kingdom Builder a few times. What should I be looking for when placing my first couple settlements? Are there synergies between the scoring rules and bonus abilities to consider? How much should I avoid being adjacent to multiple terrains?
The first turn is basically a trade-off between getting the best bonus tile (given the scoring goals in play) and minimising the risk of getting trapped, by avoiding placing in a large area of one terrain and making as few adjacencies as possible. It's often possible to do this in such a way that the bonus tile you claim guarantees you another tile next turn, regardless of your card draw.
Place according to the 3 endgame win cards. But generally keep your options open for expansion by starting with small areas you can fill up quick.