I found inspiration for this tutorial after reading this handy guide on Sparkfun's website. https://www.sparkfun.com/tutorials/59#Hot%20Plate%20Reflowing
As always, follow the instructions here at your own risk. Take all necessary precautions as you will be working with small, sharp, hot, and electrically charged parts.
Below is a quick video demonstrating the reflow soldering process (for best results try playing fullscreen in 720 or 1080p):
Step 1: What you will need
I used an Oster 12" skillet for this tutorial but other makes and models will most likely work just as well. Make sure the skillet you are using can get hot enough to melt the solder paste your are planning to use and look for ones with lids to ensure even heat distribution.
Solder Paste -
Again this can vary, I used Chip Quik Low Melting Lead Free because it was locally available and had a fairly low melting temperature but you can use whatever solder paste suits your needs. Keep in mind the maximum temperature of your particular skillet when considering pastes. If your board will be subjected to potentially high temperatures you might want to consider using a paste that reflows at a higher temperature to prevent it from melting in these extreme environments. Also be aware that solder paste can dry and become unusable if not stored correctly so be sure to read the manufacturer's instructions on storing your solder paste.
Toothpicks and Cotton Swabs - or
A Solder Stencil and Squeegee -
These are two methods of applying the solder paste to your circuit boards. You can get by as I did using a toothpick to carefully apply small dabs of solder paste to the pads that need to be soldered. This is time consuming and I would not recommend it for a production run of boards but works well for prototyping. The solder stencil method will be more efficient if you are planning to solder a more than a couple of boards but will cost you more as you will need to have a custom stencil made.
Used to grab and position the small parts. Tweezers with an anti-static coating are recommended to dissipate the buildup of static electricity away from static-sensitive parts.
Good lighting and magnification -
A bright desk lamp or direct sunlight will be sufficient enough for this project. You should also have access to some sort of magnification as it will make it easier when the process is finished to find solder bridges and inspect your work. A small jewelers 10x or 30x loupe can be found online for very little money and will provide ample magnification for this task.
Soldering iron -
This is used after the reflow process for fixing any solder bridges that might occur between component leads and for general touch ups. A iron tip with a large, flat surface area such as a chisel or hoof tip will work well for this.
Liquid Flux -
Used to help fix bridges by allowing the solder to flow more easily. I use a water soluble flux pen for easy application.
99% isopropyl alcohol -
Also known as rubbing alcohol, this can be found at most local drugstores. This will be used remove excess flux residue from the board after the soldering process.
De-soldering Wick/Braid - (optional)
Useful during the bridge removal process to soak up excess solder but is not necessarily needed.
1/8" Aluminum Plate - (optional)
This can be used to line the bottom of the skillet for more even heat distribution and easier cleaning.