I have made it a long time ago when bonuses were a lot higher and wager requirements a lot lower.
I was successful and was able able to generate nice bankroll but only in poker related games in any other casino with roulette or slots, I have never won a dime.

Until today I almost never use my own money to gamble. Try to find promotions or even better I don't look for them anymore and frequently when online I  just find a nice new promo or no deposit bonus because we have a lot of new services popping up every day and scream for awareness (this is the only way to attract players fast). The only thing which changed during these years is the bonus amounts and wagering requirements.

I am successful with poker only because this game depends on your skills and during all these years (play over 10 years) I just mastered Texas Holdem poker game.
Never won in the casino because in the longer run casino always wins. If one uses deposit bonuses or any other type of bonuses which have to wager then this is the end because you will have to play very long to fulfill these requirements and as I told above in a longer run casino will always win.