I always look for the most alert and active chicks that are clean and appear to be eating/drinking and clear eyed. Do not give in and pick out a runt, a quiet chick, a sad little chick, etc. as these are more likely to be ill. Good luck.
Decide the reason that you are looking for chicks. If you are looking at a bin in the hardware/feedstore look for active robust lively chicks. Have your had the time to research the different breeds ? What is your overall goal ? Did you build your coop and run? How much space do you have ? Bantams make eggs and take less space. Are you allowed to keep chickens where your live ?
I found a local source who is NPIP and had good feedback from other customers. I didn't want to put a small number of chicks through the shipping process so this solved the problematic decision of whether to order 25 with plans of re-homing 15 or deal with packing peanut cockerels or pay the high shipping charges at the small-order places... I was able to examine the chicks before buying and I was able to get sexed pullets (one accidental roo out of 14 chicks -- not bad!)
But yes, you want lively chicks with clean backsides. Whether you go with a big hatchery, a feed store, or a breeder really depends a great deal on what you want. I was after a small starter flock of pet-quality chickens that would produce well and resemble their respective breeds and my choices reflect those goals.
We want pet quality egg layers. I have found a few breeders locally (Utah) but they sell straight run and we can't have a rooster in city limits. We will be building the coop before we get chicks, 4x8 but we will start with 4-5 and add more when their laying slows down.
You could also split an order with other people. I've done that a couple of times when I didn't want a full order. You can order just pullets from the hatcheries. Have you been to the thread for your state, yet? In the "Where are you? Where am I?" section or whatever it's called? That's a great place to connect with people that might be in your area. You might find someone else that's planning on getting some chicks this spring.
A lot of people put their extra chickens up on Craigslist. You could also post in the section of this forum for buying and selling.
If you do pick up chicks locally, you can also check out Feathersite for chick pictures. That helps, when feed stores have assortments of many different breeds, if you want to try to pick out particular breeds. Other than that, just go for active, healthy looking chicks.
Clean, not gasping for air. Look for the perkiest ones. I like friendly, so if they seem less afraid, awesome! There are some breeds that come right to your hand, like the golden laced Cochin, but they are not good layers. My Cochin has been broody 2 times already and she's only 9 months old.lol
I like Easter Eggers, sold as Americana's, rhode island reds are my favorite layers in my flock. I want a dark layer like a welsummer or maran, but that will be next time.
I hand raised my chickens and handled them daily, they are people lovers, but all very friendly breeds. It depends what your looking for in a breed. Friendliness is important for me. I have them as pets first, eggs second. I also love the different colored eggs. Here is a pack of my eggs. The tiny one if from my d'uccle. She's so sweet.
I bought my chicks locally. The farm store owner will put in a special order if your looking for a specific breed, which I thought was awesome. He says he sells chicks all year round. His biggest selection is in the spring, no minimium order.