For detailed process instructions, check out www.paceusa.com.  My favorite technique for SMT soldering of gull-wing type packages is the Pace mini-wave process.  It uses a soldering tip that holds a small amount of solder in a spoon-like cavity.  The spoon of solder is passed over the leads of the device and the solder wicks into the joints between lead and PCB.  Make sure you read the process note on the pace web page.

Make sure to use a generous amount of liquid solder flux when you do this and a tip temperature of slightly under 700 degrees F should work well.  If you get solder bridges between pins, either you have too little flux or too much solder in the tip.

I have successfully soldered 144 lead TQFP packages on the first try without bridges or voids.  The Pace mini-wave tips are a standard size and will fit some brands other than Pace.  I must say that Pace does make an excellent iron, if you need another one.

If you want to solder PLCC and other J-leaded packages, I recommend solder paste and a hot air jet tool or carefully placed iron.

Good Luck,
Brian