It's really easy to keep a SCOBY going. However, I haven't been very happy with my results in making a nice, fizzy beverage. That requires adding some priming sugar after the initial fermentation, and then sealing in bottles. Tried reusing the Synergy kombucha bottles which have a screw-on cap, but that didn't seem to retain the carbonation adequately. I have let it go to vinegar and use it in salad dressings. In fact, there's a new SCOBY growing in the bottle that I need to remove before it gets too large.
I liked my results with green tea better than black tea. As far as fermentation process, I just brew a little under 2 quarts of tea, mix in 1/2 cup of sugar in a 1/2 gallon mason jar, then add the SCOBY when cool, and cover the top with a coffee filter secured with a rubber band, and leave it on the counter for a few days.