Financial stuff:
Dont bother with favors, table decorations, fancy invites. Noone gives a fuck and the price can escallate quickly.
Think hard about photographers: Everyone has a camera on their phone these days. Maybe just a couple of posed shots if you really want.
When you order things: Try to avoid wedding suppliers and don't mention its for a wedding. My wedding cake was three different sizes of cream gataux on a hired cake stand. Hiring the stand was the most expensive part. The gataux came from the bakery opposite venue and cost £25 total. We literally just popped in and bought them on the day of the wedding.
We had a really great band but I don't think it was appreciated. People mostly wanted to chat and catch up and didn't pay a lot of attention. In retrospect I could have saved the money.
If you have money spare- put it behind the bar. Thats what your guests want you to do- i promise.
Planning:
People don't like hanging around with nothing to do. If your doing posed photos- try to keep it to a minimum and get it over quickly
We laid on a bus to take folks from the registry office to the reception and it was money well spent. The distance between venues wasn't great but its like herding cats especially if people dont know the area.
People need some cues about what they're supposed to be doing. We didn't do a "first dance" and everyone just stood about awkwardly not knowing if it was OK for them to dance or not. Every time you want people to do something annouce it. "Please take a glass for the toast" "Please enjoy the bar" "Now we invite you to join us on the dance floor"
Interprersonal Stuff:
If family or friends have volunteered to help out or provided a service for "mates rates" you need to look after them and make them feel appreciated.
Give someone the job of circulating and making sure these people have food and drink. Give them money to spend on this.
Its a nice touch to thank them publicly and present them with a bottle of whiskey or similar.
If you have a problem relative who starts scenes- get someone to babysit them and keep them out of trouble. My bridesmaid did an excellent job of smoothing the ego of a drunken vindictive Nana.
Toileting:
You may need a bridesmaid on hand to hold your dress up when you go to the loo
When picking your date: Try and avoid it falling on your period!