Insert water on the first brewery, insert netherwart (if you are going for potions). The autooutput will output Awkward brew.
Use a pipe to send that awkward brew (or just chain brewers) to the second brewery. Now insert an item to turn the awkward brew into a "Insert potion name" Brew.
Now send that finished brew to a fluid canner and put glass bottles to retrieve the potion. Alternatively you can send the fluid to a tank which has support for the right click option to fill a potion on the fly.
Tou can add more breweries if you intend to enlengthen/strengthen/splashify the potion brew.