Good sound equipment is a base requirement--people hate and will tune out if they have a hard time hearing the players. There are a number of online resources that give advice on equipment. I find that the Dragon Talk podcasts' interviews with various RPG stream-show creaters to be interesting and worth checking out if you are looking into starting your own show. But good sound is, of course, not enough.
The field is getting crowded. One the one hand, this is good because it shows demand and there are different audiences for different styles of play.
I think the most important thing is to find a hook, something compelling that will keep people coming back and which will build a fan base. Critical Role has a compelling story, great voice acting, and yet follows the rules and is clearly D&D. Dragon Friends uses published adventure paths but has talented and funny improv comedians playing before a live audience. I think that if you are going to simply play published adventures, then you need to lean more heavily on the charisma of your players. If you have a compelling homebrew world and adventures, and a charismatic DM, that can carry a lot of slack from the players.
I'm writing this from the perspective of a fan of a number of streams. Some I've watched:
Acquisitions Incorporated (I only watch the PAX shows, first streamed RPG shows I enjoyed)
Critical Role (only the new show, I never wanted to make the commitment to catch up on the Vox Machina shows, also, four-hour live or video is too much, but now that I can follow by podcast, I listen to every episode)
Dragon Friends listened to the first two seasons.
Godsfall, one of the best-produced podcasts. Not really a streamed game. Lost of editing done. Makes it great to listen to.
Harmonquest, also not streamed, but a great mix of recorded live play with animation.
Girls, Guts, Glory. Love their original YouTube show. Have not watched since they've moved to D&D's Twitch channel.
Currently, D&D has a podcast where each episode is one popular live-stream group playing an aventure related to the MTOF book. Parallel to this, Dragon Talk is having the creators being interviewed. So the most recent episodes of Dragon Talk may be of interest to you.