Flux is the key, use plenty of flux. If the solder is balling up, sticking to the iron, refusing to stick where you want it, or otherwise causing trouble, add a bit more flux. I usually tin a pad or two in one corner, add a bit of flux, then carefully align the chip and heat the tinned pad/pin to tack the part in place. Double check the orientation and alignment, then tack another corner. Check the alignment again to make *really* sure the chip is where you want it, then solder the rest of the pins. You can usually load up a little ball of solder on the tip of the iron and then sort of drag it across the pins. Provided there is enough flux, it will tend to flow nicely over the pad and make nice joints without bridging. If you get too much on and do get a bridge, use some desoldering braid to clean it up. The braid needs flux too, normally it comes soaked in it but it dries out over time. If you dip the braid in liquid flux it works much better.

It should go without mentioning, but use rosin based flux intended for electronics, NOT the paste or liquid flux for plumbing. That stuff contains acid and will corrode stuff like leaky capacitor electrolyte. Sometimes you can find water based flux that cleans up easier, otherwise a liberal spray of flux remover, light scrubbing with a toothbrush and a final wipedown with a paper towel soaked in a bit of flux remover will clean up the mess. If you use no-clean flux you don't really *have* to remove it, but it looks a lot more professional if you do. Take care as the flux remover will dissolve and spread the flux all over the board into a thin sticky layer if you let it, that's why I wipe it down with a paper towel.