I made some necklaces so that the toggle is to be worn in the front. I added a pendant to the toggle or some charms. The necklaces are short-perhaps 18 inches long. I feel that the necklaces are too short for a front toggle. What's the right length for a front toggle?

18 inches sounds about right for a toggle front necklace. Try making a few at different lengths until it seems right to you. Just make sure there is enough weight on the toggle (by adding a pendant) and on the strand(s) of the necklace so the toggle doesn't come loose.

Hope this helps.