What's your budget? Higher end consignment shops are great assets. Thrift stores can have good options with some caveats. Buying suits new is rarely a good deal, and you can get some amazing near buy-it-for-life stuff quite inexpensively.
If you're going to be wearing suits regularly, and 1-2x per week is definitely regular, here's a good starting point. A navy blazer & gray slacks is one step to a half step down from a full suit and is a VERY flexible combination that dresses up and down so it should be the second purchase to a suit. Black is a no-no because it looks terrible in the daylight, is associated with morticians, and is a specialty item for eveningwear below a tuxedo at most. Charcoal gray is the answer there.
Navy or Charcoal Suit - DO NOT GET BLACK
Navy Blazer
Gray Wool Trousers
[2nd suit, the color you didn't go with] - DO NOT GET BLACK
White and Blue Dress Shirts
Brown and Black Shoes
Brown and Black Belt
Navy and Charcoal/black socks
A lightly worn half-canvassed wool suit and blazer won't cost a fortune but will last MUCH longer and fit you better than a cheaper suit worn regularly. The reason to get the Navy blazer is that you should not wear the jacket apart from the pants or vice versa because you don't want to make the suit unevenly worn (check a thrift store one to see if one piece looks obviously more worn than the other).
Wool and cashmere are the only things you should consider in a suit's material (a pinch of spandex is no biggie but polyester is a big no-no for many reasons). The biggest is that wool breathes very well and naturally releases odors and moisture into the air. The dry cleaners should only be for stains and a couple of times per year with that frequency.
Something else I'd add is that you should plan a significant portion of your budget to tailoring, especially if your budget is strictly in the lower end thrift store side of the coin. A good tailor can make a meh suit look really nice and help you maximize the value and comfort.