My thread is about 0.5 mm thick and i use normal sewing needles. As for my punches im using these: http://www.ebay.com/itm/1-2-4-6-Prong-Chisel-Diamond-Pro-line-Pre-Stitching-DIY-Leather-Craft-Tool-2x4mm-/390642659152?pt=LH_DefaultDomain_2&var=&hash=item5af41def50
If you scroll further down there are pictures with exact lengt and breadth of the prongs. Since the leather is quite thick they leave a diamond shaped hole which closes after a while, leaving only thin, slightly visible incisions where the sharp sides of the prongs entered. Aside from the punch i only have a round awl ( the other type is not available where i live, sadly), but i use a 1-pronged punch to do the job. I have not made a stitching groove as i intended to make the zigzag. Im currently using the saddle stitch and its the only type of stitch i have learned to use so far.
What type of thread and needle qould you recommend? If i take a thread any thicker than mine i will need new needles to go with it anyway.
Also, TXAG, your tip with pulling up one side and down the other makes sense, i will try it next time. The knot i also tried but the thread is so thin that it has no visible effect.
Unfortunately, there are no leathercraft stores anywhere close so i will have to mailorder everything. On the upside im open to suggestions ( within reasonable pricerange, of course ) since im not limited by choice that way .