Are you asking about a specific beverage. I assume you are not talking about beer since you posted in this section. Are you making mead? Cider? Wine?Mead, sorry about that.
Cool, I think I can help.
Off flavors: Ferment on the cold side: not too fussy but 60’s vs 70’s, at least keep in very low 70’s. Any higher and you will get nasty fusel alcohols which will taste hot and give you a headache.
Use a staggered nutrient schedule and degas, especially early in he process. Again not too fussy.
Be patient: it may take 4-6 weeks in primary. Keep secondary warmer like 68-72 and wait as long as it takes to clear.
Ageing:Rack carefully into tertiary and keep at cellar temps as long as you can stand, at least several months. Make sure in secondary and tertiary that carboys are filled into neck, keep very little headspace. Check that liquid still in in airlock regularly. Ok to use solid bungs in tertiary.
As far as finings go pectin enzyme in fruit meads along with letting it be a long time in secondary and cellaring is it for me and I get crystal clear every time