You have already seen how I scribe a line with the wing divider and mark the holes with the pricking iron so I'll skip that part.
I prefer to pierce the holes with the awl before sewing. I found that this way I get a straight line of holes on the back side as oppose to making one hole at a time. If I make the holes while the piece is in the stitching clamp I hold a cork on the back side to prevent the leather from distorting. An alternative is to have the piece laying on the table with a large piece of cork or underneath.
One of the keys to nice even stitching is to make each hole at a 45º angle. This off course only makes sense if you use a diamond shaped awl. To help insure a constant angle I have made a small dot with a marker on my awl shaft. When piercing this dot has to point upwards. Some people use a round awl or a dremel with a small drill bit to make the holes. I have never tried it but I know I will not be able to archive the look I want using these methods.
Go through the pictures for descriptions of each step or simply watch the video. The gunk you see on the awl when I pierce the leather is small pieces of contact cement. That happens when the cement becomes to thick. There are two solutions to this problem. Buy new contact cement or put thinner in it. I chose the first.
Lay the thread along the edge that you wish to stitch. In this case it is all the way around. Multiply this length by 4 and a little extra to get the final length of the thread.
This cork has been used alot so the center is gone. This actually makes it better as the awl dont have any extra resistance.