weddings are easy. take a fuckton of pictures of the family and randoms. get a few pics of bride and groom, say shit like "i like the light over there better" blah blah and you're good to go. people are expecting to have pics taken. get people at the tables eating dinner, dancing, etc. pics of rings, center pieces, food, drinks, the couple kissing, some shit like that. you can worry about all that before/after the ceremony though. you gotta be keyed in on the actual ring on finger, first kiss, first dance, drink, cake. then you get time to go around and snap the rest of it.
what you need to lock down is the prep. check the area its being done, indoors or outdoors, whats the weather going to be like. what type of lighting will there be, colors of the building. colors in the wedding etc.
sit down, have them say what they want and just do it. and since its for friends and its your first, 750-1000. that is cheap as fuck for wedding photos.