Because position is so incredibly important in six-max you should be more inclined to fold than do anything else in the first two seats. There are subtle differences between an UTG and UTG+1 range, but in general opening the pot in early position will lead to problems unless you are an exceptional post-flop player.
Bad opening bets are often the start of compound errors down later streets. You can ensure better and more consistent results by only playing your strongest hands out of position. Voluntarily entering pots out of position makes it harder for you to know when to value bet or bluff correctly. Being first to act amplifies your own mistakes while making it easier for your opponent to reduce theirs. Out of position you have less control, less information and fewer options than your decent opponents. In most reasonably tight six-max games you should be opening a relatively tight range.
Your firing range
Your standard UTG and UTG+1 range should generally be all pocket pairs. At the really loose tables ditch the small pocket pairs that will be tough to play post-flop against multiple players. A-K and A-Q offsuit are the daddies of the unpaired world and you should open with these on every online single six-max cash game from under the gun. K-Q and K-J suited can also be opened on a vast majority of tables. You would need to be playing tough opponents to warrant folding these holdings pre-flop.
Open limping is gross as is varying your bet sizing against decent, regular players although you can normally vary your bet sizes against fish and bad regulars. You want to avoid setting yourself up with hands that have negative implied odds. Even though I think domination is generally overrated, hands like Q-J and K-J unsuited are junk in early position and should be treated as such. If they are suited you can open with them but only if you are confident in your post-flop reads and skill advantage. You should also be aware of the table dynamic. If you are being three-bet a lot of the time then you should not open the betting. Also if you are getting called every hand by loose aggressive post-flop players then don’t open the betting.
Read Part 2...