Don't overstock you tank. Although a 10g seems big, it's actually the smallest tank you can have tropical fish in. I wouldn't add any more to that tank than a few shrimp :)
Another thing to keep in mind, you can't lump all tetras together. After owning a few types, they all have personalities. There are nervous nellies, nippers, calmer ones all based on type. My Black Neon Tetras have to be the nicest Tetras I've owned. My Red Eye Tetras are skiddish and nippy. My Glowlight Tetras are very skiddish but peaceful. I have never owned Neon Tetras and really I'm not quite interested in them lol But each type of Tetra has a different personality. Glad yours are working out!