MV,
I'd be thrilled to give my opinion, your the first who has ever asked, I try to tell my wife but she doesn't want to hear it.
I have somewhat of an unorthodox approach compared to alot of guys. My style is dictated by my personality and not neccessarily what conventional wisdom would state.
First off, I keep active as many books as the season, bonus situations and line offerings dictate. I am currently active at Pinnacle, Canbet, WSEX and CRIS. Basically each book has a distinct purpose for me. Generally speaking Pinnacle and Canbet are used for sides and totals, I know shopping around for the best number is the ideal approach, but I have found almost always I can get the best line at one of these two books anyway. In years past, I used Pinnacle, Olympic and WSEX for sides and totals, but I now worship at the Canbet alter. The other reason I use just a few books is that I don't like to spread my total bankroll too thin, I find that doing that plays with my mental outlook and that in turn hurts my bottom line. I use WSEX almost exclusively for interactives and CRIS is for some other options. From there I consider each book to have a separate bankroll go to war with, except the books I choose for sides I consider those to share money.
As for the sports I play, my success ranks with pro hoops as number one, baseball is second, hockey is next, then college basketball and finally pro foots. For pro football I never bet sides or totals before the game starts unless I have something really strong to go with, I play alot on halftime lines and I burn up the computer with interactives. When it comes to gathering information, nothing quite compares with watching part of the game before you even lay down a dollar.
As for the size of my bets, I don't have a standard formula, but I average in the range of 3% for each book, of course with interactives there are times when I have much more than that in play. I basically go with what feels comfortable, I rarely raise my bet amount level when my bankroll grows, instead I take the extra out and stay with my original amount. I try to pay myself as much as possible and not let the money in my accounts accumulate too much. Again, this goes back to my personality, nothing breaks me down mentally more than going on a nice run and making some decent return, not cashing out and then giving it all back. When I'm at my base bankroll which is certainly low for most guys, I take a combat approach to my wagers, I focus better, I pass on those leans that tempt me and I only make strong plays. I find sometimes when my roll gets a bit heavy I tend to get a little loose with my play.
I realize these approaches are not the standard way most guys who do this for a living opperate, but after 13 years I understand myself better than ever. I know I can't put myself in positions where my judgement may get clouded because of a previous loss or other stresses, I try to keep things simple and very focused. I hope you can take something from this approach and use it in your own. Good luck.