Eugene, I recommend upholstery thread. Go to the Coats & Clark brand rack of a million colors of thread and look for the one or two that have a gold and purple label that says "100% Nylon" and "Upholstery". It's very strong compared to regular thread.

If you're using a lot of it, look on ebay for a 1 lb cone of #69 bonded nylon thread.

For use with a sewing machine, you really want a #16 needle or at least a #18. I also tried a "jeans" needle which is large but it didn't work well for me.

Use 7-8 stitches per inch and go easy. Short of a commercial walking-foot machine, older all-metal home machines work best.