I'd agree with BZH - a 5-day trip doesn't really require any additional skills; to oversimplify a bit, it's just several overnighters taken without a break.

So, what do you need to figure out? First, how often you're comfortable changing clothes. Personally, a spare T-shirt and maybe spare pair of nylons shorts or pants (depends mostly on whether there's rain forecast), and an extra pair of socks, is all I take; wearing dirty clothes doesn't bother me. However, I have friends that want fresh clothes every day; some take 1 spare set (quick-dry material) and wash one every night. Others take a spare set for every day. It's all personal preference and how much weight you're willing to carry.

Second, somewhat related, is how much body cleaning you need to do. If you insist on a complete, hot wash-up every night, you'll have to practice the technique of washing from a pot (or a folding nylon basin) and figure out how much extra fuel you'll need to heat the water. If you can get by with a quick, cold wash of vital spots (i.e., face, and anywhere that might chafe), it's much easier. I fall into the latter category, and just take an extra microfiber towel for drying off. (Soap isn't needed; I just want the grit and grime rinsed away.) Naturally, you wash away from water sources and don't dump your dirty water directly into the source (especially if you use soap.) I'm not exactly sure of the ethics, but in the right circumstances, a little swim takes the place of a rinse-down. (Taking soap into a creek to lather up is a no-no.)

Beyond that, just make sure you can put together a varied enough menu that you're willing to eat it every night. Freeze-dried food and Quaker flavored oatment make that really easy.