One of the most important factors to a successful live stream is the quality of the content. Some advice is to listen to you consumers, and you will better understand what they want. Once you gather their wants and needs, then turn that feedback into content.
Your clientele is your best promoter. Use the content that they generate because they will motivate others to go out and do the same thing (the copycat effect). You should also adjust the content to certain demographics or niche audiences.
Once you have a good amount of content, and people willing to talk about that particular product, take it to the screen on a regular basis, and your consumers will keep tuning in. After a while you will begin to notice that your audience will start to grow every single time you have a live event. Incrementally, you will keep expanding your viewership.