Hire a professional to ensure that all aspects of your day are /taken care of. Photographers with experience just know for a fact the bride walking down the aisle is an important shot and so is the dad giving away his daughter right after that. Someone with experience will know this and keep shooting where as someone with little experience may not continue shooting this scene from beginning to end.
Hire a photographer that makes sense for you as a couple. Your wedding photographer is going to be with you on your entire wedding day and ensuring you are comfortable with he or she will give the best results. Yes make sure you like the photographer's imagery but being comfortable with your photographer will show in the images and show you as a couple in the best way.
In 1 paragraph describe to your wedding photographer how you envision your day, then see if they have weddings that reflect what you are hoping for. Usually, couples will say I love candid shots and a ton of details. This is a very vague answer so say something along the lines of candid shots of my family are very important to me but the relationship my mom and I have is very strong and is something I want to show in images. Also at the same time ask the photographer if they have photographed at the venue you are getting married at. If they have photographed at your venue before this will help in your decision on who to hire.
Keep communication with your photographer. Keeping your photographer “in the loop” will ensure they know your wedding day inside and out. I email my clients at least 1 or 2 times a month just checking in with them to see if there is anything new I should know. Sometimes couples say nothing has changed or sometimes couples say they ended up adding something to their wedding day. The couple may think it's not important to photography but depending what it is it may be.
Make sure you are having your wedding day, not a Pinterest wedding. I had a couple recently in a consultation say to me what is one tip I would give them to ensure that their wedding is as unique as possible. I told them to avoid Pinterest as much as possible. If you use Pinterest you end up following a styled wedding trend that may not be you as a couple.