1. Make sure that your clothes fit. No, really. It is distracting and these photos are forever. Attire, accessories and overall appearance are very important. Obviously the bride's dress should not be too low and the groom's pant hem should not be too long- you should look your absolute best on your wedding day. For guests, the same rules apply. Men make sure your suit fits, coordinates AND is appropriate for the wedding. Ladies, if you are wearing a short dress, make sure you have enough fabric to bend over, a few inches make all the difference. If you are wear a long dress, practice walking & dancing so you don't trip. And please take care of your tan lines ahead of time. And lastly, know your jumping limits.
Distracting, right? Source
2. Guests are part of the scenery, be on your best behavior. Most guests are not aware of how many photos they will be in. Touch up your makeup & make all attire adjustments in the bathroom. Keep your club dance moves at home if you don't want them to be captured forever. Don't drink your face off at the reception, that is why the professional photographer does not attend the afterparty. These sound like basic rules but I have seen some of these party fouls for myself, it does happen.
3. Again, these photos are forever. A little bit of cake on your nose is cute, a face full of smushed fondant is not. Playfully reaching for the tossing bouquet is cute, leaping like a maniac is not. Dressing up for the wedding is expected, attention-seeking attire is not (I'm looking at you, Princess Beatrice). And lastly, picking your nose is never a 'do'.
The air up there. In a plaid mini-skirt. Source