1. If you can afford it, hire a wedding planner
I like to be in control, but when I am, I worry constantly. Having a planner let me put all my worries onto her (Courtney, absolutely amazing). I didn't have to wonder if I would get things done in time, because I knew Courtney would do it. Sure, some of my stress was because I wasn't in control, but I learned to trust her and it really helped me relax.
2. Organize everything
There is a surprising amount of paperwork involved with a wedding, and you do not want to lose any of it. Every person you hire (florist, cake maker, photographers, vendor) is going to probably email you regarding the wedding. They'll want to update you, get your opinion on things, double check stuff, remind you of payments, or just see if anything has changed. You'll also be getting emails from your wedding party; concerns about clothing, whos driving who, shower planning. I highly suggest making email folders so you can quickly find any emails you might need.
Any professional emails went into "Wedding" and then because I emailed with my party so much (blame the anxiety), I divided those into separate folders as well. If I ever needed proof of an email, or to go back and look at what someone had said, I had my folders.
2.1 The binder
I had a wedding binder long before I met Courtney, and it helped me get down my vision. I'm not a very vocal or confident person, and I tend to feel like a burden asking people for things (even the people we've hired to do things for me), so being able to just show them my binder was a great help. I cut out pictures from magazines of the kind of looks I wanted, and was able to show my vision very easily.
3. Make the day of your wedding as relaxed as possible
I didn't want any stress or rushing the day of my wedding. My bridesmaids and I rented out a cabin the night before, and our hair stylists met us there. We woke up in the morning, had a nice breakfast, watched a romantic comedy, and slowly got ready. I played a pre-made playlists of all my favorite songs (bohemian rhapsody played while getting my makeup done), and when I wasn't doing something for the wedding, I crocheted or read or just chatted with my girl friends.
We had all day to get ready, and not once did I feel rushed. This really helped me go into the wedding in a calm state.
4. Remember that you aren't the host/hostess, you're the bride/groom
I love hosting parties, but I spend a lot of the time just trying to get people to like each other and wondering if everyone is having fun. I made sure to remind myself that at my wedding, all that mattered was my husband and I. I also kept repeating to myself that my guests were adults and could socialize without my help. Keeping that in mind, I was able to just enjoy my time with my friends and loved ones.
5. Accept the random freak outs, and be prepared if they happen
I have panic attacks when I'm highly anxious or stressed, so it was inevitable that I would have a few during wedding planning. Sometimes they happened after meeting with a vendor, sometimes they were completely random. But as much as they frustrated me, I accepted them and didn't berate myself for having them. It was also a big help that my then fiance knew how to help me during them, and that I kept panic attack meds on me at all times.
Hope that helps! Feel free to message me with any questions or whatever:)