Here are a few things, some obvious, some not so obvious, that I've learnt as a result of officiating at just about two hundred weddings...
Unlock Your Phone
If your planning on using your phone to play the ceremony music from, make sure you've told the person in charge of the music your password or even better taken it off for the day. There is nothing worse than having to wait while sorting out a phone. For extra credit pop, your phone on flight mode to make sure you won't get a phone call or text message notification broadcast halfway through your walk down the aisle.
Eat The Cake
Seriously after an amazing meal and a long day most likely with drinking involved a lot of people don't feel like cake. Which is a shame because no doubt a lot of hard work went into making the cake and it probably tastes bloody delicious. So why not cut the cake straight after the ceremony and serve it as a round of canapes, with or without champagne, while everyone can truly enjoy it? Another plus is that it means your photographer doesn't have to hang around waiting for you to cut the cake or you don't have to stage a fake cutting of the cake before your time with the photographer runs out.
Do Double Duty With Your Flowers
If you're trying to stretch your budget when it comes to getting the most of your flowers. Why not talk to your florist about using the flowers from your table settings for your ceremony space as well.
Drinks
Whether it's water, juice or booze if it's hot during summer chances are people will appreciate a drink of some kind. Also, it gives people something to do while waiting without the awkward milling around.
Create a Focal Point
If you're planning on getting married outside chances are the spot you have picked is gorgeous but might be missing something to create a focal point and help make it feel special. If you add some elements, which don't need to be expensive, like a rug, barrels, hay bales for seating or a back drop it will help to make it obvious as to where the ceremony will be happening and elevate the whole feel of it.
Footwear
Grass, if you're outside, and heels are not a good combo. Go for wedges, flats or those funny looking upside down mini wine glasses that slip on your heels to stop you sinking into the ground.
Keeping Cool
If you're outside and it's summer chances are it's going to be hot. One trick I've seen to help out with this is if your planning on having programs make them into fans, your guests will appreciate it.