I'm certainly not an expert when it comes to laying, but I've always made money in the long run from it and wb has shown that it can be quite lucrative with his system threads.
If you lay longer prices then it's a real roller coaster ride at times and can be hard to deal with emotionally as you can make profit for three months on the trot and then have it wiped away in the space of a couple of days.
I don't lay horses bigger then 3/1 as I just don't like betting at short odds and I don't like roller coasters very much The shorter the price the less of an over lay there is and the smoother the ride. If you lay short price favs then a lot of the time your betting at near enough to SP so there isn't much of an overlay at all.
If you think you've found a good system then just paper trade it and let it run for at least a few hundred bets, anything less is pretty pointless. I would stick to horses near the head of the market to start with as it's better for the ol' ticker.
Some people see things that are and ask, Why? Some people dream of things that never were and ask, Why not? Some people have to go to work and don't have time for all that ...
George Carlin