Get the grip size sorted, everything else is personal preference.
A guide here, but I'd recommend getting him to try a few They have two ratings for grip size, numbers 1 to 5 or in inches (I think from 3ish to 4 7/8ish, I forget). You can of course pad out a grip, but it becomes tricky to feel the bevels in the grip - basically, the grip rounds out and you cna't tell which way the face is pointing.
Larger headed racquets tend to be more powerful for slower swing speeds (i.e. beginners) but have less touch. Most are so good now that even cheap ones will be perfectly servicable, but try to avoid aluminium racquets as these bend and aren't always that responsive. As others have said, look at the decent manufacturers, alongside Head I've found cheaper Wilsons to be reasonable - I played with a 40 quid Wilson Staff for 5 years (although this may be more thna you want to spend).
Avoid anything called a 'player's racquet' as these will reward high, accurate repeatable swing speeds but punish anything else.
Again, get the correct grip as you can induce all sorts of muscular and nerve problems with the wrong size over time.
eta: Leafster had it covered, although smuttily.