Hey I don't think you need a big bankroll, I started doing bonuses with only 75
euros and haven't looked back since.
In the beginning I only did the small bonuses with the lowest wagering requirements and built-up so I could move onto the bigger bonuses. The time this took allowed me to develop confidence in my playing and strategy.
Initially I was very conservative, betting the minimum, and patiently completing wagering requirements. It is definitely a boring way to try to make some money but its not hard, frustrating at times yes.
All I do is play to the guide and try to speed through the WR as fast as possible and these days I hardly have to think how to play its so monotonous.
My goals in doing this are just to make a bit of spare cash. I'm not looking to win big (don't get me wrong I wouldn't turn it down) and its not a career, just a bit of fun with some benefits.
I don't know how many of these bonuses you've done or what your targets are but the only advice I can give (it worked for me) is to start small and built a good foundation.
Best of luck,
yobes.