I'm playing ToA with my friends and I am playing a human variant. Any tips on feats to take to make my character more support oriented would be appreciated, also recommendations for sub classes.

War Caster is good, as Support you'll likely be throwing up Concentration-based spells every combat, so you'll want that advantage.

Healer, Inspiring Leader, Magic Initiate.

Magic Initiate is probably better in my opinion because you get extra cantrips which can be support/utility cantrips and one-per-day-for-free spell of your choice which could be something like Goodberry, Cure Wounds, Healing Word, etc.

As for subclasses... Abjuration. Level 6 you can project a ward to take blows and protect an ally, you can counterspell more effectively. There's also Divination for the starting Portent ability allowing you to change rolls made by you, an ally or an enemy. The Transmuter's 6th and 14th level features are useful: give a transmuter's stone to an ally to provide them with a benefit like increased speed or a damage resistance and the 14th level effect can you restore somebody to life or take somebody that is wounded and fully recover them to full health and free of disease, poison and curses.

Support is a rather vague term so it depends on your playstyle and type of support. You can support your allies with utility, with buffs, by debuffing the enemy, countering the enemy or by controlling the enemy. Which subclass you should use will depend on which of these you want to focus on. Although ultimately it's not super important - you're ability to support will mostly come from spells and there are good support spells in all schools of magic.

You could also go Transmuter and use a bunch of buffing spells that way.

If you make your Wisdom high and grab a Perception and Investigation proficiency, you would be able to be a good trap finder with Dungeon Delver (If you take this route, you might want to get the Light Cantrip). Along those same lines, Observant will get you an Intelligence buff while helping you read people's lips and have +5 Passive Perception. 

I do agree with Cyber Mind on Magic Initiate though. If you take it, go druid and take Mending, Guidance, and Goodberry. 

For your Subclass, I would recommend Necromancy or Conjuration, early on they are pretty under powered, but later on they can really pay off.

For my wizard I chose Mage Initiate for my first feat and selected the Cleric spell list.

This allowed me to get Guidance, Spare the Dying and Cure Wounds.

I then chose the School of Divination which allows me to influence the battlefield via the Portent ability.

At level 10 you get some very interest utilities to be able to see into the Ethereal Plane, See invisibility and read any language. Although there will be niche opportunities for this to shine, its great to have it and not need it and need it and not have it.

As a Diviner you also get to offer support outside of combat through the use of divination spells which allow you to gather information on all sorts of things. Need to find a key in a room to unlock a door? Locate Object. Interrogating an NPC for information? Detect Thoughts. Need to listen in on a conversation? Arcane Eye + Observant feat.

One of the aspects that make me like the School of Divination so much is the Expert Divination ability you get at level 6 (ability below). This means you can do all of your reconnaissance before or after a battle without it always being so harsh with using up your spell slots. 

"Beginning at 6th level, casting divination spells comes so easily to you that it expends only a fraction of your spellcasting efforts. When you cast a divination spell of 2nd level or higher using a spell slot, you regain one expended spell slot. The slot you regain must be of a level lower than the spell you cast and can’t be higher than 5th level."

 In addition to all of the above you can of course gain all of the combat buffing/debuffing spells as any wizard can. 

For me, I feel like all of the above allows me to offer support both in and out of combat and in the game I play in, there is usually an equal amount of both.

But that's just my 2 copper pieces on the matter. :)