Managing bank roll was my bigges tproblem. I always wanted too much to soon. Now I split it. For example, some of my tipsters are from betrush site and have different stakings(one does flat, other scalable 1-10 and so more) so the hardest part is to adjust stakes. Reasoning for that is quite clear: you dont want tipster killing profit of your other just beacuse stakes aren't the same.
So now I have 50 000e for betting, thats my total bank that I have reserved. In order to be sure longterm, I bet 100e per unit if staking is 1-10 and if it's flat, I take it 5-10(500e). As you can see, I didn't take strict 2% beacuse I don't need it. I had issues with placing that much money without losing odds( I use Asians only with specific tipsters) and with this staking I earn enough. Considering bad streaks, the biggest question is where to quit some tipster. If he losses 5 units you say: he must come back, he is good and then he goes 10 down and you area already frustrated and dont know what I do. That is why I really pay attention to their history and reactions in such streaks and if he increased number of picks or stake while in past he kept his cool, I dump him. If someone goes to minus and keeps losing 8th or 9th pick but he gives same ammount of picks and all, I will still work with him, even if he goes to -12 which is my bottom line.  If he increases picks or stakes, I dump him at -5 already.

Considering bookies behavior, there is plenty of books regarding that and none of them is right. Bookies are adapting, changing their rules so it's becoming harder and harder to beat them them. For example I know bookmaker in UK bookie and his company shift odds according to markers. THey mark winners and when they stake(even small ammounts), they collapse odds. On the other side, some other bookies react differently. Example is Pinnacle who moves margin when staked ammount on bet is reached( you bet 700 on itf they downgrade the odds) so it all depends on bookmaker and market. Third option is bet365 where everyone waits live offer in order to place more.
My biggest problem, after money managment, were limits. Asians are hard to beat, but really hard. If someone can beat them, he is tipster for 2-3 years and then he goes betting by himself. Also they take lot of money as all Asian tipsters who I met wanted 100e or more per flat unit of profit which was too much for me. Beacuse of that, I focused on bookmakers with bit lower odds and payout rate but wider offer. I used some informations regarding local soccer leagues, won something on ITF and low level tennis and then limits came. You get into situation that you have excellent ITF tipster but you cannot work with him beacuse your accs keeps getting limited, you opened on all your friends family etc. and you need to change strategy. Luckily, some guys who were in it longer then me gave me source who now provides me accs for bet365(easiest to beat) and that's what's keeping me over the water. I still have issues beacuse if I lose bet365 now, I must switch completely to Asians and I am not ready for it yet, I just have 1 good tipster with 8% ROi.
To make it more real to you, 8% on Asians is awesome. If I bet his pick 1000e, his average is 17 in month, my profit is only around 1500 and when we deduct his fee, around 1200, way less than what I earn now.

There is lot of room for mistakes for bettors as they are possible on each step but it can be really good job. I work from home, if I go to beach or somewhere i place bets from phone, dont have working hours, can take break whenever I want and it's really profitable. With betting I earn 6 times average salary in my country and that makes all these 8 years worth it.