For most people, a car is their second-most valuable possession, just behind their house.
And yet, many Americans routinely hand their keys over to valet parking attendants -- total strangers in nylon vests.
"It's more like valet parking roulette," valet parking attendant Ed Ryder told ABC News' "20/20." "Who knows who you're giving the keys to, really?"
Ryder dished the dirt on valets, and what really happens to your car when you hand it over.
"Rough driving is not unusual," Ryder said. "They could lose your keys. They could scratch it, dent it, crash it. Things can go missing inside the car."
Ryder is currently developing a venture called "Real Valet Control" that would educate drivers on how to reduce the chances of problems with valets, such as lost keys, damage and missing items.
Check out some of his tips below to ensure that when you pick up your car from the valet stand, it's in the same condition you left it in.
Watch the full story on "20/20" Friday, May 9 at 10 p.m. ET.
1. Tip Pre-Emptively
Valet parking doesn't pay big bucks. Ryder said he's paid just $3.83 an hour. So, the quickest way to a valet's heart is often through their wallet.
"Start by putting a tip on the dash," Ryder said. "What that does is it helps to influence the level of care your car's about to receive. If you only tip at the end, there's no way you can undo the care or lack of care."
2. Take Out Your Valuables
It may seem like common sense, but people often forget to remove their valuables. "I would recommend clearing your car out of all items of value before you valet park just to take this issue out of the equation," Ryder said. "Why invite the problem?"
3. Walk Through a Checklist of Your Car with the Valet
To make sure the valet realizes you mean business, walk through a checklist of the car's condition with them before handing them the keys. "What I would recommend doing is having your own valet form. And you hand it to the valet, and you say fill out the pre-existing damage and initial that for me, please," Ryder said. It lets them know that when you return you will check for damage before you drive away.
4. Tell Them You'll Need Your Car Back
"In the past at our property, I know that joy rides were happening," Ryder said. "They would confirm with a guest whether they would need their car any further for the evening." If a guest responded no, he said, that would signal to valets that they could take the car home. To prevent this, you can tell a valet that you will be needing your car, even if you won't.
5. Think Twice About Bringing a Car with a Stick Shift
"A lot of valets don't know how to drive a manual transmission," Ryder said. "They may end up learning and practicing on your car."
6. Check For Damage BEFORE You Leave
According to Ryder, some valets will let you leave without telling you about any damage that may have occurred. "And once you're off the lot, that's it," he said. "You can pretty much forget about getting any compensation for that damage."
7. $1 Is a Really Bad Tip
If you plan to bring your car to the same valet stand in the future, the valet parkers remember if you left a bad tip. "Two dollars is ... cheap. Three dollars is better," Ryder said. "Four dollars is appreciated more. Five dollars is great. Ten dollars is lavish. Twenty dollars is making our day. If you tip nothing, then ... we really hate you."
Confessions of a Valet Parker: Tips to Keep Your Car Safe