Kick the Tires
Work with prospective employees on a test-basis first
It's one thing to look at a portfolio, résumé, code example, or previous work. It's another thing to actually work with someone. Whenever possible, take potential new team members out for a "test drive."
Before we hire anyone we give them a small project to chew on first. We see how they handle the project, how they communicate, how they work, etc. Working with someone as they design or code a few screens will give you a ton of insight. You'll learn pretty quickly whether or not the right vibe is there.
Scheduling can be tough for this sort of thing but even if it's for just 20 or 40 hours, it's better than nothing. If it's a good or bad fit, it will be obvious. And if not, both sides save themselves a lot of trouble and risk by testing out the situation first.
Try a small test assignment to start. Don't leap in with all of your work at once. Give your new [virtual assistant] a test project or two to work on and see how the chemistry develops. In the beginning, it's too easy to gloss over potential problems with rose-colored glasses. Make it clear this is a test run.—Suzanne Falter-Barns, author/creativity expert
(from How To Find And Keep The Perfect VA)