My advice differs slightly from what these guys are saying. I recommend finding a wingman (use the Find a Wingman section - there are dozens in London) and simply going out with them. Some of the best stuff I've learned is from going out and getting stuck in with other guys, mostly because, as human beings, we learn better from each other than we do from a book.

Speaking of which, try not to be duped into thinking "The Rules of the Game is the way to go" or"direct is best" or "Mystery Method is the greatest" or anything. Every method has its own merits and disadvantages - the key is to find what works for you and you can only do that by having a go.