1. You'll want to start with a sausage that has at least 20% fat in it. Otherwise it will have a chalky texture if it's too lean.
2. Double grind it if you can. That will help the texture.
3. Use a cure. Insta-cure #1 is the standard, and 0.25% by weight is the standard ratio. Total salt by weight (plain salt plus cure) should be 2% minimum for safety. Unless you're planning on it taking more than 30 days to cure (and it really shouldn't), don't use Cure #2.
4. Use a needle to remove any air pockets after stuffing. If you stuff the sausage properly, there should be very few if any air pockets.
5. We always cold smoked our sausage and air dried it. Hot smoking for dried sausage seems like a bad idea, but I don't know for sure as I've never done it that way. We cold smoked ours for 3-4 hours and then let it air dry. Usually takes 10-18 days depending on the weather.
6. High humidity is ok and actually preferred. If the air is too dry, you'll end up with case hardening, where the outside layer is dry but it's still raw in the middle. If that happens, and it likely will, vacuum pack it and freeze it. It will even out in about a month. Not sure why this works, but it does.
7. Watch for mold. White powdery mold is ok, wipe it off with vodka. Green, black, or slimy mold is very bad and that product should be tossed if it's been that way for a while. You can wipe them down with vodka too if you catch it early and hope it doesn't come back. If it does, trash it.