As to comboing: Comboing is almost universally accepted as a part of the Knight, and even the developers condone it, so therefore, it is legal according to the majority of the community. Above all, it is the community that decides what is and isn't cheating, within reason.

Potting: It isn't really something that can be taught.

In PK:

Pot red if you are under attack serious enough to risk death in the next few seconds. (unless you're cocky enough to think you can take your target down with you, in which case, pot blue and mail me the result )

Pot blue if you are under half mana and not in danger of dying. Keep your mana as full as possible, I can't count the number of times a target escaped because they had one hit left and I had no mana. If your priest is good and not shouting that hes lagging over vent/TS,(goldceo.com) keep potting blue to finish off your targets ASAP, but throw an hp pot in here and there if you must to make sure you do not enter redball range.

In boss hunting/XP:

Only pot blue if you have one or two SD's left, depending on your max mana.

Pot red if you are below half health (if in cz.) You may want to pot more often depending on how many of the opposing race is out and what boss you are fighting.

Note: Feel Boring with practise by yourself? Just buy the cheapest knight noah, Knigth powerleveling and Knight bronze to save your time. Just have a try!