Which direction would you recommend someone who is interested in getting a char that focuses on acid/poison damage?
It has to be at least somewhat beginner friendly. Dont have lots of gear.
Is an acid/poison pet build ok? 
Dark one set supports poison damage and it is easy to farm,because it drops from specific mobs.It took me like two hours to get all pieces.You can create Cabalist or even Witch Hunter.
Nightblade + Occultist is probably the easiest acid/poison build to get started with. Blood of Dreeg, Veil of Shadow + Night’s Chill and Curse of Frailty + Vulnerability are great skills to build around. If you want to play melee you can grab the dual wield procs and Lethal Assault to beef up your damage. If you prefer a caster playstyle, just get Dreeg’s Evil Eye with Focused Gaze. Shadow Strike is a good utility skill that you could also use as your main attack.
As for devotion, pick up Manticore and Murmur on your way to Abomination. Akeron’s Scorpion and Eye of the Guardian are good as well.
But you need a pretty decent char in ultimate to start farming for that set.
I would do a cabalist and focus on Ravenous Earth and Dreegs evil eye (DEE)
https://www.grimtools.com/db/items/8626 this item will let you do acid/poison Ravenous Earth, and you then use the DEE transmuter as a secondary “bomb”
something like this https://www.grimtools.com/calc/vNQJKQj2
(medal is faction blueprint, one can use the Basilisk crests too)
Here is a dual wielding witch hunter I made in like 10 minutes
https://www.grimtools.com/calc/RZRalAKV
rings you buy blueprint from secret vendor in bloodgrove. Almost everything else is faction items, or random greens. The weapon and medals are farmable MI’s look for affixes that gives acid dmg and physical > acid conversion, and defensive stuff