Hi Ben.
Advice as follows.
1. Make sure you are in (or can easily reach) a decent catchment area (100k+ population quite dense). Don't spread your round out too wide (Warwickshire and Oxfordshire is a no - you want a 3 mile radius for your main concentration of work)
2. Keep an eye out for a second hand wheelie bin cleaning van at a decent price (I personally wouldn't use a trailer). Get it signwritten so that it stands out like a police car.
3. Work out where the bin rounds are. Wednesday empty has to be cleaned on Wednesday. Be careful not to overload certain days.
4. Leaflet like mad - aim to drop 20,000 leaflets in your first 3 months - not as easy as it sounds.
Bin cleaning is very organic. People will come out to you in the street, especially if you're the only one. It is hard graft - poncey shiners have got nothing on bin cleaners
Also, don't be afraid to charge for people who call for bin cleaning miles away. I charge £25 for a clean 10 miles away. Take it or leave it.
If you do want to start then now is the time. Don't leave it 'til the Summer.
Good luck.