Nobody will tell you. Do you see how liquidty looks like these days? Absolutely shite If we talk football or other minor sports. Let's say you found a niche, make some money, would you tell anyone? No, you would keep betting and praying no one finds out.
I had profitable stategies before but edges are found and disappear quicker than you may think. No one is willing to share such things. Basic stuff you mentioned (lay draw) could work ages ago but for sure not now.
All "working" systems posted here and there are useless, basically tested over just a little sample, cause even betting evens it's possible to get on winning streak of 1-2k bets even if you don't bet +EV.
If you would find an edge on BF you would know how much time it takes. I can estimate for you. I found some edges on BF. In average it took me between 6 months to 12 months of 10-15 hrs a day work to find one. Spending such amount of time, would you share the slighest info? Don't think so.