Not trying to be awkward, but your question is a bit 'openended'. Are you just taking up the hobby, and do you already have an outfit? If you have bought a caravan and are unsure of towing safely, then enter one of the Courses offered by both main Clubs. They will tell you all you wish to know, and more importantly, give you 'hands on' experience.
If you are still at the 'pipe dream' stage, then visit a good few Shows, and ask as many questions you like. Again, both Clubs usually have stalls where you can show your 'ignorance' without any fear of castigation. If you have the car/4x4 but are unsure of what you can safely tow, then again ask at as many Shows you can, before making a choice of van.
