clean the area alot. then reflow the points. maybe cut a piece of leed off an new component or some copper wire and reflow that into the pool. not enough to reflow onto. use a small piece of insulated wire and jump the component to another point on the board. make sure to inspect the whole board for other bad solder joints, poor joints, etc.
be clean. dont have copious solder on your tip. dont want it to fly around. make sure your tip is clean and tinned. look the whole board over for any solder joints that look bad. wiggle the ports to look for loose connections. wiggle power. if you have to flow any port joints than do all of that port. if one could move wiggle they all will. thats stress.
clean tip. maybe even clean the board. sometimes older solder will have a varnishy covering. prolly burn off when reflow. just reflow the solder. maybe add a TINY bit if it looks like they used too little.
dont leave your iron plugged in any longer that you use it. mess up alot of irons and tips by leaving them plugged in durring breaks.
dont try the same spot many times. reclean. wait. let it cool. clean it more. let it cool. be patient.
keep your metal rings, jewely, screwdriver, etc away from the board.
ground yourself on a metal water pipe or something by touching it... dont shuffle on carpet... dont play with your hair on a dry day..
touch the irons tip to the lead more than just the joint.
and let us know how it goes..