What mph said is pretty huge for longer distance shooting, do not move, no strafing, no walking back and forth. Up close feel free to strafe all you want. Don't mag dump unless you are close, otherwise burst fire 4-10 rounds at a time depending on distance. I prefer automatic guns and manually tapping the trigger to burst fire, others on here are pretty beastly using guns with a burst fire mode. You can change the fire mode on guns by pressing either down or up on the d-pad I can't remember which one.
As far as game modes domination is the same as Cod domination. Three flags you capture, all within close proximity to each other, no vehicles, and fluctuating spawn points (ie no defined sides of the map). You can have enemies spawn in behind you.
Team deathmatch - pretty basic, no vehicles
Both of those modes are focused on gunplay so its a good way to get gun kills and attachments.
Since you played bc2 rush will be the easiest to understand in battlefield world.
Conquest is 3 or more flags to capture, larger maps, vehicles, the more flags you hold the quicker the enemy tickets will be depleted, when your tickets are zero you lose.
Obliteration- similar to rush but there are 3 mcoms for each team and a neutral bomb that you have to pick up and plant on the enemy mcoms. there is a 20 min time limit.
I don't play the other modes so I won't speak to those.
Edit: I just saw pen's post...mine is pretty similar I guess I took too long to type on my phone Edited by hsv - 11/27/13 at 11:53am