After reviewing most of the Best Slot Machine Strategies online, I have come to the conclusion that they do not offer any advantages to online players whatsoever. Most slot machine strategies are written with the bricks and mortar casinos in mind.
In my humble opinion, the best slot machine strategy, online in any case is to sign up with the pg slot which offers the best deposit bonus and reoccurring bonuses. The percentages offered in payouts during online play varies between each casino by as much as 15%, so do your research and play at the casinos which will reward your time and money with the greater payouts.
There are a few strategies around which will tell you that if you count the amount of spins between wins that it is possible to “predict” when a win is around the corner and to increase your bet size accordingly, to be honest I really do not know if this would work, as all casinos use complicated algorithms to ensure that all spins are completely random.
One tip I have picked up though is to ensure that the slot that you are going to play, pays out using an equal ratio method, by that I mean that It will pay out the same percentages for using 2 coins as it will for playing 10 coins, for example you play 2 coins and win 6 coins, then for an equal ratio slot you should expect a 30 coin win whilst using 10 coins, some slots online reduce the percentage when you are playing a smaller amount of coins, to try and tempt you into playing with more coins than you should.
If you do find a strategy that works for you, I would suggest that you only use it whilst you are winning, when you do start losing, that is the time to either hunt for another strategy, change machines or in extreme cases go to another casino.