It is only a day, but can hold good memories. Have an inexpensive (it doesn't have to be small to be so), personal, fun day.
Prepare for marriage itself beforehand, but be aware that there are always surprises and often a steep learning curve after the day. I feel a person is never really fully prepared for the realities ahead. You are making a very important promise that day. Treat this life long promise to your partner seriously and stick to your word for the rest of your life. There will be days ahead that will certainly test it, but it can all be worked through.
Basically, don't be selfish: respect your partner. Keep communication open. Don't go to bed angry with the other. Be quick to forgive and make amends.
Good:
1. Didn't spend much at all on the wedding dress...nothing in fact.
2. meal: cold cuts & cheese, veggie and fruit trays, juice, coffee & tea. No caterer. Family & friends kept things going.
3. Wedding cake done by family & a friend.
4. Have willing friends and family help out. Designate people to certain tasks. Ask well in advance to confirm, check closer to the day.
5. We invited a lot of people. I should have invited more. We had many leftovers...
It was a celebration and I wanted to share it. I have never regretted that. I should have invited those passing by on the street.

haha
6. We kept everything (including some personal favorite food choices) very simple and personal, and really inexpensive. It did not cost an arm and a leg.
7. Keep decorations simple, but personal.
8. We did not do a dance and booze. We didn't have either by choice and it was an excellent decision.
9.Be done early in the day. You don't want to be tired when you leave.
10. Pay for it all yourself.
11. Consider opinions. Use only those that you think are constructive. I think opinions could have been much more had money for the wedding come from family.
10. Someone pushed to be invited only because they were friends with the parents (someone I was not a fan of) and that was frustrating at the time. If that is the case, say a firm no if you wish, but it really didn't hurt me in the end for them to come and everyone was happy. Looking back, I now consider my initial reaction selfish.
11. I was happy to invite families with children (even large families). That should be a part of marriage...families, so I welcomed them as a unit. Less hassles for them, more happiness for all. It was not a question in my mind.
12. I did my own makeup.
Changes:
1. Make sure your hairdresser is super clear about what you want. Do a trial visit.
2. Get a good and creative photographer. See their work beforehand and discuss what pictures you might like. Agree on a price that suits you. It doesn't have to break you. On that note, get some guests to take impromptu pictures. We had some given to us as gifts. They can be fun memories.
3. Make sure you have someone to do the physical decorating for you. It saves a lot of hassles the day before.
4. I had entertained having cheesecake instead of a standard white cake that day, but forgot. That would have been easier decorating wise, and so very tasty.
5. I would tell guests to come as they are...jeans & t-shirt, lol...no need to dress up unless they wanted to. Relax.
If you are planning, take breaks, have fun. If you get stressed, designate, take a break. Make notes. Keep it simple. Enjoy.