Probably one of the biggest things is to iron out your score running system. If you're using the electronic scoreboards, it's definitely a must to check the software ahead of time, work out your input system, make sure everything is up to date. I think you have to renew stuff with it (if you want technical support at least) and sometimes people are borrowing those from other gyms, etc, so it's really key to have all that work out, because scoring glitches are a nightmare and can significantly delay meets. Getting the scores online as quickly as possible is also always appreciated, and sometimes that's not always straightforward (might need to export files to Excel, etc) so you want to figure out ahead of time who has the skills to do that.
Work out a basic ranking system for positions. Some positions are best done by people who know what is going on in gymnastics. So you want your experienced people in those positions. Others, anyone can do, but adults will be preferable, so you want to allocate your adults to those. Finally you have the jobs that kids can do, i.e. walking the cards from one table to another or such.
Be ready to be firm with people. There's plenty of opportunity for people (parents, coaches, people who work at the venue, photographers, whatever) to try and do things that'll interfere or cause problems. You have to have a take charge person who can deal with these people professionally but firmly so they don't cause issues.
That's just really basic, I mean, if you have any more specific questions. Definitely be reasonable about times and try to start and finish on time. If there's time at the end before scores are in (inevitable) plan to have a handstand contest or music and dancing or some other kind of activity so everyone is not just sitting around. People get really antsy. It is better to have them watching their kid do something when they drove five hours or whatever, than to have them sitting there wondering what is taking so long. Personally in lieu of doing a goody bag full of useless things I would rather see a meet director spend the money to give each kid a healthy snack such as a water bottle, granola bar, and banana. But people are looking for something that starts and finishes on time, not a lot of downtime, parents LOVE the scoreboards with the kid's name, gym, score but my experience with those hasn't been great. But everyone is videotaping nowadays, they love to get those establishing shots so if you can make the march in really great or something especially for the younger kids. But on time is key. On time. On time.