Remember, as with any makeup job, the ironic goal is that brides on their wedding days should strive to look natural rather than "made up." Makeup is designed to enhance natural features already present on the woman's face, not replace or manufacture them. (Leave that to the Hollywood makeup artists.) On a wedding day, above all others, there will be pictures and videos taken constantly and the bride will want to look radiant in each and every one of them.
Proper skin care in the weeks and months leading up to the wedding is essential to get the skin in the best condition possible in order to achieve optimal results on the target day. All the usual advice for general good health applies to skin care as well: drink the proper amount of water, eat nourishing foods, get full night's sleep every night, and exercise regularly.
An overall word of warning about wedding day makeup (which applies to other areas such as hairstyle) is not to do anything out of the ordinary at the last minute. The morning of the wedding is not the time for experimentation. Defiitely hold a dress rehearsal the week before to test the exact look and makeup that will be done on the special day.
If you break out with acne before the wedding (and this is a possibility since many experts say stress can precipitate a breakout), use your normal methods of healing and camouflage. Also, it is best to stay out of the sun anytime preceding the momentous day as a burn could easily turn into uneven tanning and peeling skin which will be difficult to hide or deal with.
Various factors will affect how you choose to apply makeup on the wedding day. The style of the dress makes a difference as the more elaborate the dress, the more elaborate the makeup can be to match it. Daytime weddings versus nighttime weddings play a role here too. Nighttime weddings are considered more formal so more makeup used than the amount for a daytime wedding will seem acceptable. Also, the lighting will be different between the two so you want to take that into account as well.
You definitely want a long-lasting makeup as it will be on for many hours and it may be difficult to slip away for touch up jobs. Even if it were easy to do that, the photographer would find a way of snapping a candid shot of you just when you needed the fix up the most. Finally, waterproof makeup will be in order because you want to preserve your perfect look through your tears of joy.