THE most important thing when letting your property is the inventory. Ask the letting agents to show you a copy of one of their inventories which should include a comprehensive condition report. I manage my own properties and also use a letting agent and the test of the agent is when a tenant moves out and a new one moves in. If the inventory and condition report is done right along with the conditions on the contracts then all should run smoothly.
In response to the previous post about getting your money back from tenants that have not paid and now live in council property, forget it. I have been in this situation and after court action (which you need an agent to chase daily) and you can't get blood out of a stone. Fortunately for me I got a guarantor so I took him to court and got an 'attachment of earnings' order so am slowly but surely getting the money back out of his wages every month.
Dont be afraid to ask your agent for examples of how they have dealt with issues and ensure their paperwork is watertight and ask for guarantor as a condition from your tenant. The market is buoyant at the moment so you shouldn't have a problem taking your pick of the best tenants.
Hope this helps.
