One strategy you could try with 40+ is to stop at 3 correct lays for the day.

That means as long as you don't hit a winner more than once every 2 weeks you should be ok.

But if you blindly lay 40+ you will lose over time mainly becasue some of those horses are better chances than that.

Also it can be very hard laying those horses on betfair as you will usually have to give up very big odds (100+) to lay them as people only take very generous overlays.

Stick to laying the favs. Overall it is as close to breakeven as you will get and a loss won't hurt too much.

I am currently lookng at just laying one of the 2 favs each race on betfair. Sometimes your lucky and neither win.... other times you get it wrong but as long as your right more often then not you will make a profit.

Personally I think laying $10+ horses on betfair is just asking for trouble unless you are being very careful with your form analysis. There is no quick easy way to do it.

Good Luck.