You can expect a lot of ups and downs in SNG's , the best strategy is to not check the cashier often.

OK. How many do you think I should play before I start looking at +/- ?

2K games?

SNGs are, by nature, a high variance game. There are a lot of showdowns in any one game, so you are involved in a large number of situations where you are no more than a 70% or so favorite and are playing for all your chips. At times, the swings you'll go through seem unnatural and almost sickening. To compound the problem, a lot of players are continuously trying to get better and bad players often go broke. This brings the average level of competition up and therefore lowers a winning player's advantage over the field.

Breakeven stretches and downswings can last well over 1,000 games if you are playing at the highest levels. Even at lower levels, 2,000 game breakeven stretches have been noted. This means that to have an idea of your true win rate, you may need thousands of games. This sometimes makes it difficult for new players to know whether or not they are really beating the games. Unfortunately, that's the nature of the game we play. The best thing to do is constantly try to improve, play as your skill and bankroll allow, and simply not worry too much about swings or what your ROI is. It takes so long for numbers to normalize that your game will often change or you will move up in stakes before they've had a chance to. So it's almost futile to spend too much time worrying about how many games you've broken even over or what your ROI is. Of course this advice is more pertinent the higher you play, since higher stakes are where skill advantages are the smallest, and thusly, swings are the largest.