I did a bit of reasearch on Silas' Reenacting Links and thought I'd share a bit of what I learned as well as what my impression will be. I am in the 9th Virginia Company C and our unit is pretty loose with new recruits like myself, so I need to be careful with this kind of aspect in the hobby.
You want to represent a soldier on campaighn most of the time, unless at winter camp or garrison. Shelter such as shelter halves were unheard of as they were too heavy or even too scarce for their Yankee counter parts. I will get one though because I hate the rain and sleeping under the dining fly is a great way to get stepped on it the morning. A Shebang or just a ground cloth tied between some trees as protection from the rain will be OK. You could also just spoon with some pards when it gets cold.
Jackets and Jacket color is a big issue in some units. Ours does not want Butternut in the ranks. Your jacket should be made of natural dyes. Ben Tart makes some reasoable blanks which gives you some room to customize it. The Butternut color is created through the prosses of the natural grey dye in the jacket being exposed to the sunlight for an extensive period of time. However, it could have been an original dye. Make sure your buttons are tarnished. They would bury them or pee on them to make them less shiny. Less shiny means less of a target. Most of your jacket should be hand sewn. New reenactors should buy a sutlers row jacket to start, then upgrade.
Hats can get expensive, especially the G. Starbuck hats. Kepis are a no no in the ranks of common soldiers. You should have either a beehive, slouch or a bummer. I made the mistake of buying a kepi, but you learn from your mistakes and move on. Sleeping hats should be woolen and hand knitten. Find your grandma or someone who can knit and ask themif they could knit you one. Be polite.
There are many shirts out there. WW&Co. make a good CS issue shirt kit. If you get a second shirt, it should be homespun and a square pattern. Family Heirloom Weavers make some nice fabric.