A good stance is very important. It will protect you from your opponents attacks while simultaneously keeping you in a position to setup your own attacks. A good stance should be low with the legs wide, this helps to distribute the weight better and increase balance. Square stances are more defensive, while lead-leg stances are better for offense. There is no 1 correct stance; your stance should change based on your opponents position.

I strongly suggest keeping the same leg in front for your lead-leg stance (don't be a switch hitter!)