Have you done any similar SMD / PCB type soldering before? I'd suggest you get out some broken electronics and practice a bit before going back to the devo, get your temp and amount of flux dialed in better.
Also remember, it's almost always best to add a bit of your new solder your working with to the old joint before trying to separate it (be it two wires, a wire to a via, a component to a pad or whatever). The fresh solder won't properly liquidity and mix with the old solder till it's hot all the way threw, this way you can see exactly when it's totally liquid and you don't rip pads / traces off pulling to soon.
Also, what type of tip are you using? Conical / points are the worst for this type of soldering, try a wedge it a spade shape or even flat if it's all you have. And always always use a good liquid flux, even on already soldered connections and pre-tinned pad!
