Variance is huge so volume is crucial, tight BRM and super aggressive is the way to go but do watch the BRM it is not straightforward, a few wins when the wheel stops on a large pay-out causes fluctuations always to the positive or profit side, they are impossible to calculate or repeat reliably (a pure luck aspect of this game) they can be deceptive and often encourage a player to play higher buy-ins than the roll should allow. For true BRM you need to calculate the odds of occurrence of the 4X 6X etc and factor in your win probability to those instances, also note how much you pay for the luck / chance aspect, EG. 3 players $1 buy-in each contest a $2 prize, $1 minus the rake pays for the larger prize pools. Therefore for every $1 you buy-in assuming rake average of 7% for the house you pay $0.26 to the jackpot or lottery fund (26%).
That example is approximate, a closer mathematical outlook would be like this, for twister prize-pool structure of a $10 buy-in you contest (when all is considered) an average pay-out of $28 about 6.6% house rake.
Some basic math:
4X 15%
6X 8%
20X 0.1%
To break even you need to win 35% (volume) of games you play
40% win rate should give you a 10% edge
Playing with a 40% win rate you have a 30% chance to lose 50 buy-ins during 1000 Games
The absence of ICM needs to be considered as it changes the ratio of luck vs skill.
Deviation of the game: 4.5 compared to 5.5 in 180 man SnG
Have you considered playing super turbo heads up SnG to lessen the deviation, your style and attitude may give you a better edge there?
Because of the high variance volume is far more significant than money won due to the multiplication factor, so of the 700 games you have played how many did you win?
Good luck in the venture keep us posted, don't loose that bank roll its good now
Just my opinion but I think you should stop playing $15 buy-ins at your current bank roll. I'm not familiar with Spin n Go my opinions assume they are similar to iPoker's twister.