Good general advice from others. If you want specifics here is what I've done.
1. Medicated chick starter for new chicks (I bought medicated to avoid pasty butt but the chicks still got it so I'm not sure this was necessary).
2. After a few days add grit and introduce bugs or grass clippings or vegetable scraps, if you want. Not necessary but fun. Grit must be added if feeding these non-feed items.
3. Keep fresh water available all the time. I was amazed that I had to clean out or refill their waterer nearly twice a day--they drink and spill a lot. Try raising the waterer to keep poop out of it--so long as it's at chest level it's okay. Watch to be sure all birds can comfortably dip their beaks in to drink. When they are big enough to move out to the coop purchase a large, 5-gallon waterer so you only have to fill it every few days. Again, keep raising it to chest height to keep bedding out of it. If you're in a climate cold enough to freeze water in winter search BYC for how to make a homemade water-heater. It works great! Or, buy two waterers and keep one thawing in the house all the time and switch them at least once a day.
4. Switch to layer pellets when they're approaching laying age (around 20 weeks). I find pellets lead to less mess and waste than crumbles. I use Purina Layena Pellets because it's available at the closest store and the best price. You may want to try purchasing from a nearby feed mill, if this is possible. Some say this is more cost effective, depends on how far you have to drive and local prices, of course.
5. Provide purchased feed free will (always available). Chickens won't overeat the way some fowl will. As a supplement I throw in kitchen scraps every day to encourage the birds to turn under their bedding (using deep litter method). I keep those large tubs that yogurt or cottage cheese come in and fill them as I'm cooking. Each day my birds get about two of these. They clean up the scraps in 10-15 minutes. I like that my scraps aren't being wasted and that the bedding is getting turned under so no smell from fresh manure. But, feeding scraps isn't necessary. (I limit scraps to fruit and vegetables, no meat or dairy.)
6. If you have trouble with thin-shelled eggs you can add oyster shell for calcium. I provided it free choice in a bowl and nobody ever ate it. So, I finally had to resort to grinding it with my mortar-and-pestle and then adding the powder to the feed pellets. Took care of the thin shell problem--I notice a difference if I skip doing this but I have 3-yr-old ISA Browns that are pas their peak egg production years.
7. Free range the chickens as much as you can--good for their system to get bugs and greens and good for your feed bill. I feed one 40 lb bag of Layena every 2-3 weeks for 7 birds in the summer when they're ranging more; whereas I go through a 40 lb bag for the same birds every 1-2 weeks in the winter. Those numbers are very approximate and will vary for you depending on what kind of birds you have--I have two big birds, four medium-sized, and one bantam.
8. In the winter I also put out suet cakes (cheap type at discount store for wild birds) in a suet cake feeder for when they're bored in the coop since mine appear afraid of snow. Or, you can save fat from cooking and mix it with wild bird seed to make your own suet cakes.
9. I do not provide any grit because my birds free range. I have an old gravel driveway that I see them pecking around in to get their grit, even in winter.
I hope that info helps you. Of course this info is specific to my flock, different things may be a better option for you depending on where you live and what kinds of birds you have. Enjoy your chickens, though, they're great fun for the whole family. My cousin says watching her flock is as soothing to her as watching fish in an aquarium is for other people!