If ever I'm in the position of planning a wedding, there are some things I want to remember.
In the grand scheme of marriage, the wedding is really the least interesting :). Keep it fun, keep it casual, don't get stressed.
Speaking of stressed, I think the worst thing would be to have the day be surrounded by stress. Who wants to look back on their wedding day and remember how stressful it was. Keep it fun, keep it casual, don't get stressed.
Trying to please everyone will leave someone disappointed, it's inevitable. Be careful to not constantly have that person be you. Respectfully let others be disappointed too. Keep it fun, keep it casual, don't get stressed.
Break the mold. Who says your public commitment has to look like everyone expects it to? Those people don't need to be invited and/or they can be disappointed. You do not have to spend a lot of money on "wedding things" that you don't even want or need. Keep it fun, keep it casual, don't get stressed.
Speaking of money. Don't try to save money by "delegating" the costs to family and friends. By this is I mean, don't ask people to do things for free, don't ask them if they would bring 12 veggie trays but oh hey do it with their own money, generally just don't ask people to spend money on you and if they offer to spend money on you be hella grateful because that person is a lovely person.
Keep it fun, keep it casual, don't get stressed.
As an extra, maybe try to not make a date until you have collected all/most of the things that you need to spend money on. You know, like set a moderate monthly wedding budget and slowly collect the goods, THEN set the date so that there isn't a deadline and you end up spending more money than is wise to. But who am I kidding, I'm a procrastinator, I'll leave everything to the last minute whether I wait to set a date or not :P