For starters, you need to know what parts are required, and what different winches are available...the main two are electric and hydraulic.
Electric winches are (relatively) easy to fit, then run off battery. They can run when your engine is not running, but can drain your battery, so many regular users opt for twin battery and split charging kit. Problems with electric winches include water damnage caused to motor or electrical solenoids. motors can burn out too.
Hydraulic winches are a bit more involved to fit, as you have to fit some source of Hydraulic power, most people use a power steering pump. Hydraulic winches have faster line speeds, can sometimes pull more than an electric winch, are a million times less susceptible to water damage. Hydraulic winches need the engine to be running in order to work.
Winch rating is usually 1.5 times the weight of your car, ie a 2 ton car requires a 3 ton winch. most people go with around 9000lbs ( over 4tons).
The best make (in my opinion) is Warn, however, they tend to be much more expensive than other winches. Sup[erwinch are also good.
I beleive Ramsey are a good hydraulic winch company, as are milemarker, however I HAVE NEVER USED OR OWNED A HYDRAULIC WINCH.]
Hopefully somebody who has, can give more advice.
I have had a Warn 9.5ti before, which was very good, I now have a Warn 9.5 xp which is also very good and fast.
The main winch used for competiotions is the Warn 8274, a monster of a winch, which can be extensively modified for higher performance.
The cable on the winch can either be a steel cable, which is strong, relatively maintenance free, and very cheap to replace, or synthetic rope, which is very light, but very expensive. I beleive synthetic rope floats too. synthetic rope can melt on some winches, which have a brake inside the rope drum.
The main benefit of paying around £200 for synthetic rope, as opposed to £40 for steel, is that if a steel cable snaps, it will recoil at great speed and could easily kill somebody. A synthetic rope will fall to the ground if it snaps.
Winch mount is dependent on tast, requirements and budget, but the main thing is that it is well constructed, and mounted correctly. The mount should anchor your winch to the chassis, in order to take the loads imposed on it. Some winches are just bolted onto bumpers - if used, the bumpers can simply peel away from the car, or they can shear at the wrong time, causing injury etc.
You'll also need come battery cable, to connect your winch up to your battery and you could fit an isolation solenoid too (switch on your dash which either supplies power, or cuts power to your winch)
You'll also need to buy a winching kit, which usually consists of a few strops, shackles, tree savers and snatch block. If you're in recovery, Im sure you'll have these anyway.
Dont forget a decent pair of thick leather gloves too.
Some cheaper winches are available, but the general concensus (I beleive) is that you get what you pay for. Google it and you'll se pics of many a cheap Chinese winch in bits. There are many satisfied owners of these winches too, but if it were me, I'd surf ebay etc for a second hand Warn winch, in good condition, rather than a brand new cheap winch, which may let you down.
heres a couple of examples - bear in mind that these winches are over £1000 brand new...
Warn Winch 9.5 XP Electric Winch - 6HP / 9500LB - NEW on eBay (end time 15-Jun-10 18:30:09 BST)
WARN 9.5TI WINCH 6 MONTHS OLD on eBay (end time 16-Jun-10 20:03:13 BST)
