There are many different staking plans to use when laying horses. The laying to a liability can sometimes be very profitable and should be taken into consideration.
I personally never lay over 4/1 or decimal 5 when laying on Betfair this way, if a selections drifts in price and then wins, I always know my maximum liability.
Yes you will get more horses that drift and then lose but you will also get the occasional horse that drifts and then goes on to win, putting you out of pocket.
Lets say you have a betting bank of £1000 and the horse is 4/1 you should use 5% of your bank for the liability, ie £50 so the stake on a 4/1 horse would be £12.50, not massive but safe.
If the horse was evens, then the stake would be £50.
This is a very safe way to lay horses. If you want to be more aggressive with your staking then, lay to a liability of 10% of your bank.
With this staking method, if you are following shorter priced horses, ie. between evens and 3/1, you should be making a decent profit over time, so long as the strike rate is good.
Source:
www.betplacement.co.uk