I always like to emphasise that the groom speech is a unique opportunity to stand up and say lovely things about people who are, and were, important in your life, and that opportunity needs to be seized with maximum enthusiasm. Fingers crossed won't get this chance again, and so it then becomes an exercise in trying to work out who those people are, and more importantly who they are not.
The trouble is many grooms get a little bit carried away, and before you know they have a speech which would make the Bible look like a quick read. The length of the speech is absolutely critical to its success, make it too short, and everyone will be wondering why you bothered at all, make it too long, and people's joie de vivre will disappear faster than the table wine.
The problem is twofold: including too many people, and talking about them in too much detail - or even worse a combination of the two. You need to keep the list of people you're going to talk about to a sensible level: key family and friends only, and please don't mention the caterers or the flower guys - they should be thanking you. Whatever you say about them has to be done in a really efficient way, and a lot of grooms aren't great at efficient communication. By all means go into greater detail about parents, but you can't write chapter and verse about the best man or ushers, or go into granular detail about the bridesmaids. Many see it as an opportunity to recount hilarious stories from there past. It's not. This is celebrating the occasion and the person you're marrying, not a romp through your Ibiza glory days.
Your speech should really be no longer than 1500 words at the absolute maximum, and an easy way to see where you're getting it wrong is to add up how many words you've written about the best man, and compare that to how many words you've written about your now wife. All too frequently they're about the same, and that means you're off the mark. Keep it succinct, keep it efficient, and keep the stories from your Glastonbury Gabba techno tent days for the bar.