First of, welcome to the Dented Helmet. You've come to the right place.
I usually tell people who are getting into building a Fett costume to determine which one you're going for, and you have a few options; such as: ESB, RoTJ, RoTJ SE, Pre Pro 1, 2, or 3 + a few others to choose from.
Second, regarding parts of the build, I usually recommend to starters to start with the soft parts, as this is the base layer of the entire build. Flight suit and vest, belt boxes and spats. With getting the flight suit out of the way, you can determine any tailoring adjustments that need to be made. Arkady
here on the TDH makes the soft parts I just mentioned. I'm not aware of anyone else currently outside of the community. If you have the sewing skills, you can make a flight suit out of scrubs or a red cap jump suit, or from an alternative vendor on Etsy, depending on the type of accuracy you're going for.
Armor wise, you have a few options. Viva Fett, Neo Fett are a couple of names that come to mind for hard parts. Alternatively, if you have some diy and motivation, you can use templates to cut out the body armor out of sintra and heat form it to your body.