The Only strategy we can use Playing Slot machines? is to have being responsible gamblers and have self control and also Knows when to quit.
The exit strategy is different and you only need to set your fixed limits which you can't exceed while gambling but if you talk about slot games then most probably you don't apply ample of strategies there and just wish you win on that bet.But for sure every gambler must have self control because it could be too risky if you have gone beyond your loss suffering limits so must take care of that thing.Sometimes martingale strategy works for quite times also we can use this a basis to have systematic betting although this doesn't guarantee but it's quite fun to play using this sometimes if we talk about betting using it on short time period. Yeah it's not good to chase your money lose on your playtime but if you can afford to do that since you are a whale then maybe it's somehow a good place where you can practice your patience since sometimes we need to lose to learn something new which can help us win next time around.
Just kidding by the way you are right luck is key factor which will determine you will win or loose in luck based games. 
