How to stop a cold sore before it comes?

I can kind of tell that I'm going to get one so I want to know how to stop it now before it actually develops into one. I have these L-Lysine tablet things which are meant to reduce the chances or getting cold sores and help to reduce the frequency of them and I can usually take one of them when I think I'm getting one and they won't form, but this time I think I mustn't have noticed it quickly because it's kind of more into the process than usual (like usually I can just feel the tingling and all but now there's a slight bump on my lip) so I don't know if it will work properly. Anyways, what other ways can I stop it into developing into a proper one??