There are a lot of options. You can freeze the leaves whole, you can make pesto out of it and freeze the pesto, you can put the basil into a food processor with a little olive oil and freeze that (to be used as pesto, in soups, atop various dishes... at a later time), or you can dry the leaves in a dehydrator. I am not a big fan of dried basil. I can tell you that freezing the leaves whole or freezing pesto works wonderful. I freeze basil leaves until I have enough to make a big patch of pesto at one time. If you have enough I would try a couple different ways and see which you are most happy with.

I pick mine, wash it and put in ziplock bags to freeze then I have fresh basil all winter. I just crush it in the bag and add to cooking.