My basic approach (I think I explained in early posts), is to look at factors which don't seem to be accounted for in the odds (or miscalculated) i.e., impact of transition from one surface to another, collateral form etc. Put them together, and decide on what the basic oddsline should be. This is an artform I suppose, as I like to decide what odds I would be happy to back/lay at are. If the bookies/bf odds are sufficiently out of kilter, i.e., say 7% then I would look at in more detail to ensure I haven't missed anything (niggling injury etc). If my more detailed revised odds are still out of kilter it is worth a bet. I then place bet into a database I have written and a custom bot drips my bet into the market trying to get best odds. Once bet fully placed, I submit here. Obviously there are several weak markets where my bets don't get matched fully in which case they do not get posted here.
In summary, it is about finding what I consider "value" prices.
All the data is available at WTA / ATP tour, Davis cup and ITF websites - a quick google should find them (not sure if links allowed to be posted)?