Hey Rocky B,
Tailgating off of Youngblood's excellent suggestions, you have to make a committed, conscientious effort to utilize combinations if that's the direction you want to go. When incorporating Youngblood's recommendations, I suggest utilizing combinations of AT LEAST three punches. If you do a lot of one-twos, well, that's not really "combination punching" in my book. To me, it's gotta be at least three. With that said, don't get me wrong, strategically/tactically speaking, one-twos have many salient functions in the scheme of ring things. So, definitely don't disregard them.

Anyway, here are a few three-punch combos to get you started:
1. Jab-cross-lead hook
2. Lead hook-cross-lead hook
3. Cross-lead hook-cross
4. Lead hook-rear uppercut-lead hook
5. Jab-overhand-lead shovel hook to the ribs (specifically to the liver or spleen depending on if you're southpaw or orthodox).

Good luck...

Take Care,
Lito