The thing to remember is the solder will only stick well to a hot surface. Make sure the surface of both things you want to solder is hot, apply solder. Also you can't really get the heat transferred to the surfaces you want to head without a little solder, so make sure the iron has a bit of solder on the end to allow for maximum heat transfer.
For surface mount I recommend putting a dab of solder on only one pad, slide the part onto the pad as you heat it, then apply solder to the 2nd pad. Trying to prime both pads beforehand gets you into trouble.