Random list. Some is preventative.
Depending on your industry, substance abuse can be common. Learn to spot the signs if issues could affect your business, have a testing policy, and make note of it in the job postings.
The earliest sign of that is lots of missed / late days, always with plausible reasons. The implausibility being that there were reasons several times a month.
If you have a service where employee safety is critical, fire people if they repeatedly don't follow safety rules.
If safety is critical and they simply don't understand how to do things safely. There are times when someone doesn't have the ability to take what you are telling and showing them, and adapt it to different situations like they'll need to be able to do. Some people just don't have the mechanical aptitude where it counts. Not a bad worker, just a bad fit for the job.
Background check. Do your own too... google for things like the employee name and L&I claim. The last company I worked for had someone fake a couple injuries and their L&I claims lasted for three years. When it all started, they googled the guy and found court records of him doing the same thing to his last employer.
Situational compliance with anything important. The person who will learn all the things that need to be done and then asks a coworker, "So how much of that do we really need to do?"
Fudging timecards will usually start early if it's going to happen at all. Keep an eye on that at first for sure.
Don't be afraid to secretly check in on new workers from time to time. Seeing how they perform when unsupervised is important and an early indicator.
