1. They don't start with a realistic budget
I see it time and time again, eager couples book the venue, spash out on a great dress and then realise there are lots of expenses they either didn't know about or had unrealistic expectations on. It's so important to research and get quotes right at the beginning so you know exactly what you need to budget for.
2. They don't trust their suppliers
You have chosen your suppliers based on good reviews, recommendations and a good reputation (hopefully,) couples need to then trust that those people will do their job. They've done it so many times before, over-planning with your suppliers can be a waste of time. Make sure you express your style, your personality, your relationship. Show them images of what you like and you should be set.
3. They aim for a 'pinterest' wedding
There are just so many ideas out there on pinterest and the internet, some couples don't realise that some of these amazing ideas were designed and prepared by some incredibly talented people with equally incredible budgets. Where couples go wrong is when they try to incorporate too much into their day or change their minds when they see something better. Once something has been organised couples need to stop looking at new ideas in that area.
4. They are expecting perfect
Nothing is ever perfect, hopefully you won't have a storm on your wedding day or something go drastically wrong but understand that you cant control everything or everyone. Trust you have put the right people in place to fix up any problems as they arise, carry on smiling when a baby cries out in the middle of the vows and don't get annoyed that your schedule isn't running exactly on time.
5. Being too stressed on the day
Brides are notorious for trying to do too much or manage too many people on their wedding day. What ends up happening that bride misses all the little details she has planned, she cant relax and enjoy herself and the day goes by in a flash. Make sure you have professionals lined up to deal with all the day-of tasks.
6. Losing focus and forgetting what it's about
Brides get caught up in the details, the dress, the flowers etc and sometimes lose focus on what brought them to this point. I always remind couples that it doesn't matter what happens on the wedding day, the most important thing is that you get to marry the love of your life, everything else is secondary.
7. They try to please too many people
Most couples have family members who want to have some input into their wedding whether it be by passing down a treasured item or having ideas on how things should be done. Brides especially have a hard time sticking to their own plans and desires especially if those family members are contributing financially. Couples will sometimes need to gently remind those people that this is their special day.