It takes lots of practice to get consistant results for making tongs, making anything for that matter. My instructor's take on it, was to make 50 copies of whatever you are making, throw away the first 45 and make 50 more based on the best 5 of the first batch. Repeat. Once you've done this about 5000 times you can consider that item mastered. Repeat the process for everything you want make in a consistant manner.
About 30 more and I'll have my first 50 tongs made!