SEA FOAM is a pretty good treatment. It can be used in all types of engines two or four stroke. It isn't that expensive and 1 can is more than enough for a motorcycle. It will clean the tank and entire fuel system. It can be purchased at most automotive supply stores. STA-BIL is good treatment for storage.
Most bikes don't need treatment. If yours predates lead-free gas, you can buy treatments that compensate for lack of lead, as older bikes depend on it to cushion their valves. Buy the best quality gas you can find. Higher octane is unimportant, unless your manual suggests it. Good luck!