[Nix]

Sounds like basic sabaki-movement. As I understand, your problem is keeping a correct distance. If you move in while pivoting (something which I personally prefer), you will of course need to focus on close-distance techniques, such as shita tsuki, hiza geri, gedan mawashi, uchi momo geri, etc. It is also vital to control the opponent, either by putting your hand on his arm, or if allowed grab his sleeve. You can also use your control to push the opponent further away from you, in order to increase the distance and execute a mawashi geri jodan, for example.

Usually simply pivoting is not enough; you need to move your feet also, so you end up in a comfortable kumite no kamae facing the opponent. You can move in, to the side as you please, as long as your counter-attacks suits the distance.