I've never tried Suitsupply, but they are building quite a following.
Go onto youtube and type in Harry Rosen and fit of a suit to pull up the 2 videos on how a suit should fit, then go down to The Bay and try on a couple of different brands to confirm your size. Go up and down at least one suit size to confirm the shoulders. If you stand 5"7' and under, go for a "Short" and if you are average height, go for a "Regular". If you're around 6ft, you'll probably need a "Tall".
Only adjustment that can't be made is the shoulders. They can adjust the length, but it won't look right if they chop of more than an inch. If the waist has to be taken in any more than 2 inches, it also doesn't look right.
If the difference between your chest and waist is greater than 8 inches, you should go made to measure or bespoke to get a proper fit. That will put you up over $1,000 though.
As for colour, get a solid charcoal grey. It's the most versatile. Stay away from black as your only colour. Too harsh in the day, especially if you have a light complexion. Besides, black is what everyone wears in the service industry. You don't want to be mistaken for a waiter.
I think if you can swing it, I think Samuelsohn suits at Harry Rosen start at $1095. They really are a bargain for what you get.