I am (or was) a pro photographer. I've got over 50 weddings under my belt. My .02 is to decline the invitation to shoot their wedding. It is a once in a lifetime event and I cant tell you how many horror stories I've heard about friends/family shooting weddings.
There is a reason people are willing to spend a couple grand for a good photographer.
Once the wedding is over the bride and groom will have two things. A overpriced dress that sits in a box for the rest of their lives and the pictures. Good wedding photographs are worth 10 times what was paid up front.
That being said, if you still do decide to do this, make sure you are prepared.
Main camera and a couple lenses
Back-up camera and a couple lenses.
TWO flash units and PLENTY of batteries.
A couple extra memory cards. (SHOOT A MINIMUM OF 500 FRAMES, FULL RESOLUTION)
Lens hood is a necessity for an outdoor wedding!
Do you know how to pose a group?
Do you know how to pose a couple?
Do you know how to CONTROL a group?
Do you know how to light a group?
Can you do all that FAST w/ grandmas, aunts, uncles ect looking over your shoulder and giving advice?
Is the reception in or out?
Do you know how to shoot CONFIDENTLY in everything from heavy overcast to bright, direct sun?
Do you have to capability and knowhow to shoot w/ more than one flash?
Do you know how to shoot fast? Can you time your shots well? (DONT MISS THAT KISS!! DONT MISS THE CAKE CUT!!)
Most importantly, can you GUARANTEE 100% that you and none of your equipment will fail to miss ANYTHING?
When I shot, I charged a minimum of 2K and usually cleared 5K by the time everything was done. I was good, and people like my style. That being said, I still got VERY stressed out, I still missed things occasionally, and my top of the line equipment (hasselblad) would let me down now and again.
After 50 plus weddings, I decided that it wasnt worth it, no matter how much people were willing to pay me.