I want to make a neclace.. what is the best way to attatch a normal clasp to the string? Can i just tie it on?

Answer 1

Yes. Tie it with a square knot and then "dab" it with a coating of clear nail polish before trimming the loose ends.

Answer 2

Yes, you can, but depending on the style you are making, a barrel clasp or other type other than a ring clasp might be a better choice.

This website has good pictures of some of the clasps that you can use:
http://www.bjcraftsupplies.com/jewelryFindings/clasps01.asp