Johnf,
For the first year after taking advise from our selling agents we let through a management company. They did not get us any bookings for the whole year we were with them, and were not particularly interested. They had their money after all.Subsequently we have gone it alone.
If you have a few hours to spare, surf the web. There are many sites who offer 2-3 months free advertising.We advertise on a total of 8 sites(plus own web site) and only pay for 3. We also advertise in 2 magazines which are not cheap, but have given us good returns.
Advertise using 'business cards'. Look for special deals. Managed to get 500 card for £9!!!! great to leave in Dr's/dentist etc. Be careful though because you can tied up in a contract if you tick the wrong box.
Its very time consuming but we have managed to ger 11 weeks booked this year which is 11 more than last year when we did nothing but rely on agents.