well i'm not very good at long essays but i would recommend playing a more math based game and brush up on ICM. i have a 4 part sit n go blueprint in market if you're interested, its really in depth and tells you most of the things you need to know about sit n gos. but once you get the math right and start winning more than losing then you should start adding more tables, maybe add one each session till you reach the amount you can handle without compromising play. mainly though you should just play tight and not get involved in too many marginal spots and try and maintain fold equity. chips lost are a lot more valuable than chips gained in sit n gos.