Many people have issues with writing the Best Man Speech, and for good reason - to do it well takes, skill, practice and a good helping of wit. It's little wonder that it can prove a real headache for those 'lucky' enough to be made best man. As I've said many times in posts, and pages on this site, your best friend is time, and now we find ourselves at the beginning of the year you'll probably have at least 4 months before the fear and panic of the final countdown to D-Day. So, with that in mind, and if you're planning on writing it yourself, you're firstly considering the initial outline of the speech.
The problem with thinking of a best man speech outline is that you need to understand what kind of speech you want form the very beginning. If you're thinning about going down the tried and tested 'a couple of stories, a bit about the bride and marriage advice' route, then you really don't have to think about the speech until the night before, because no matter who much thought you put into that little lot, it will be an unmitigated failure.
A really great Best Man Speech needs to be considered as a whole and not as series of component parts. When I'm devising a plan for a speech, and all my speeches are created uniquely, I begin to think about how to bring all the elements of who this guy is and what he's about into one central theme, and then build the speech around that. You need to have a beginning and an end, but you shouldn't have any other boxes to tick. At the same time I want to know a little about the groom, but not so much I could write a book about him. So, any traits or facts need to be conveyed in the most succinct and funny way possible. And that's the key to a successful Best Man Speech: succinct funniness.
So, stop thinking of the speech as a well trodden pathway form beginning to end, instead when you're thinking about the best man speech outline, simply think about the outline of the groom and use that as your guide. Once you know what you want to highlight, then weave a pathway through his characteristics and stories, using a minimalistic approach. A quick and easy way to map out a structure is to look for some well prepared templates, but be warned: some are better than others.
This is an opportunity to have fun and entertain, it's not a sales pitch, so forget the best man speech outline, and just tell a bloody good story.