Hi Mook
Decide on your overall budget and decide which layout will suit your needs best.
How many berths?
Do you want a fixed bed?
An end washroom?
Side dinette?
Have a good look around a few dealers forecourts, you are usually allowed to look inside both new and used caravans so take your time to decide what you want and what you don't need.
Do you need a full size cooker with oven and grill?
A microwave oven?
Large washroom, or do you intend to use on-site facilities?
TV aerial points and 230v sockets?
External BBQ point?
How much storage and what size wardrobe?
Make a checklist of the things that you want, find what make and model offers them in a caravan that you like the look of inside and out at a price that suits your budget and find out how heavy the caravan of your choice will be.
If you decide to purchase, haggle like mad to get a reduced price because if you don't ask you won't get and you're not out to make friends or gain the salepersons approval, so be firm and polite because you won't see the sales staff again after you've signed on the dotted line.
When you've knocked the price down a bit, try for extras such as an awning, leisure battery, Aquaroll and Wastemaster. Don't forget that the market is shrinking which gives serious buyers like yourself an advantage so make the salesperson work hard for that sale, don't show too much enthusiasm even if the caravan is fantastic and never be scared to stay silent so that the salesperson has to do the talking.
Have fun choosing your caravan which should be within the weight range of the type of car that you want.
Do the same sort of thing with your towcar purchase, get that price down by haggling!
Good Luck