Some of this depends on what his job will be or in what settings he will mostly wear the suit, but here’s my 2cents
- Prefer gray first. Navy second. That is by far the best order. Lightweight wool is the best fabric. It's good in all seasons.
- Look at Hickey Freeman or Hart Shaffner Marx. They have more traditional cuts, and fabrics, and colors. Nordstrom is a very good place to look first. Center vents seem to be popular these days. I never liked them, and if you're really stout, I'd avoid them. Don't go the double-breasted route, especially if you're not tall (at least a real 6 feet).
- By all means, *it cannot be emphasized enough*, if he is shorter and stockier, it is likely he needs a 38-42 SHORT. Don't get talked into a "regular" by the store or salesman. The bottom hem of the jacket should just touch his relaxed, cupped fingers at his side (meaning it should reach the end of his palm). If it is longer than that, (hanging to the second knuckle), it will make him look like he is wearing a thrift shop or hand-me-down suit. This point is absolutely critical and lots of stores don't carry enough of the "short" sizes....they just sell suits that don't fit to the guys who are shorter, which makes them look ridiculous. You will instantly see this if you go to Nordstroms first, and then somewhere else. (If it doesn't say short on the size label, it's not.)
- Take a cue from the others his age wherever he expects to work, but take more of a cue from those who are 15 years older there. That's who you want to look like.
- Don't get caught up in showing how trim you are at age 22. You wan't the suit to fit decently for 6-8 years, and you also want to be able to move comfortably and not have to take the jacket off all the time to feel decent. Go for looser rather than more snug in the fitting. If the store doesn't have multiple selections around your size so you can compare one size larger or smaller (42S vs 40S vs 39S), find another store.
- Don't shy away from a suit that costs a bit more than you planned on. I never once regretted spending more for a good suit. Always felt great about it. And take your time shopping. These things are expensive, important, and you're stuck with it for a long time.
Good luck.