I've done my fair share of driveway paint jobs and there are a lot of tricks involved to make them successful.
Other than keeping an eye on the weather forecast, the main one is to do all your prep work the day before so you can paint first thing in the morning, before the wind, bugs and sun show up. You also need to build some sort of framework to hold a tarp above the car. That keeps any leaves or other tree crap from falling in the paint from above and to block the sun if (when) the paint job takes longer than expected. Lastly, the cement needs to be watered down to keep from rasing dust as you walk around while painting.
I generally have pretty good success with driveway paint jobs, but some unexpected weather moved in during this one and I was forced to rush the job. I'd say it's a pretty good 15 foot paint job, but that's about it.
Tom