Do yourself a favor and don't give up your day job. You ask if you can play 3/6 FLHE professionally. I did it, but that was back in the '90's. These days, from what I've seen, not so much. Back then, FLHE was the only game in town, and so the rake wasn't so brutal.
These days cardrooms, especially "captive audience" rooms offer 3/6 as a "courtesy" to those who are afraid of no-limit action. They rake the living
hell out of these games. That's short sighted stupidity on their part. Sure, these fish don't understand how rake impacts their
equity, but we're discussing recreational players who think range is where the deer and antelope play, equity has something to do with real estate.
However, you can't fool fish forever, and they eventually stop coming when their buy-ins seem to melt away even though they've been hitting cards. I would eliminate rake altogether from these low stakes FL games and give them a chance to win something, keep 'em around to graduate to the NL games.
So how can I beat this game 8 out of 10 times everytime?
That you would even think to ask such a question shows you're
far from ready to do this. The only ways I know to beat 3/6 FLHE 8 out of 10 sessions every time will all land you in jail.