So, you have decided to hire a professional photographer for your wedding to preserve the precious moments of your big day. Good for you!
I am sure you have done your research -- you love the style of the photographer, and his/her/their package fits your needs and budget. You may have checked out the references from past clients and even asked about the equipment.
What else can you do to ensure you get what you pay for? Here's an idea -- unplug your wedding! Have your guests put down their cameras, smart phones, tablets, and any other image-capturing device and be present during those sacred moments. Here's a parody if you are not convinced: (great job, SLF Weddings!)
A special note to the Faux-tographers: I understand how you'd like to help your friend(s) while beefing up your portfolio. Go find your own gig! Leave your cameras at home when you are invited as a guest. The fact that you were not hired by your friends does not mean that they don't love your pictures; they'd rather you be witness to their holy matrimony. (Ok, maybe they don't like your work, and all the more reasons that you shouldn't shoot at their wedding.)
As courtesy and my preference not to mix work with personal engagements, I have stopped bringing cameras to weddings when I am a guest. I do have my iPhone with me, but it mostly stays in my purse, especially during the ceremony. I want the wedding party to see my face and not the back of my phone. I want to be in the joyous moment and be moved by the beautiful union. The only times I would take out my phone would be when guests are free to roam around, and I see (1) impressive decorations worth sharing on Instagram; or (2) moments that are too funny to pass, like this one:
See the 2nd person on the left (in black) behind the flowers? He wasn't even shooting the couple! I happened to be in the front row, but I swear there were another 50 phones and cameras behind me! So, I didn't see my friends signing their marriage license, but I sincerely hope that the professional photographer captured the moment properly. (I just assumed that the one on ladder was the hired pro!??)
Unplug your wedding. I know it's difficult to implement. After all, some people get separation anxiety for not looking at their phones every 15 seconds. Try to follow the principal; ask your guests to refrain from taking pictures (esp. with flash) and videos during important moments. Tell them that the professional photographer will take a picture of the whole crowd and put down the phone if they want their faces in it.
While it's frustrating to be blocked by guests, I also find it amusing as the wedding photographer -- see this aunt photo-bombing the couple at their first dance. I am sure she got a picture of me shooting her too, and I hope she too found it amusing. Ultimately, it's your choice and your photographer would shoot to the best of his/her abilities. I can assure you that it's still better than relying on Uncle Bob... LOL.