First off let’s start with the skills, and let's focus on the ones that could be considered promising and combos that should work especially early on.
Contagion & Essence Drain
This is the most obvious combination that came from POE1 and will be a basic choice for Chaos Damage over time builds. Both of those skills deal Chaos Damage over time and if monsters die while affected by Contagion, ALL Chaos DOT debuffs, including Essence Drain, will spread to nearby enemies and renew the duration.
This combo will excel at clearing large packs, where Essence Drain will be a main damage source and should be pretty nice for early game.
Skeletal Warrior, Skeletal Cleric, Skeletal Arsonist
These are basic minions that you might want to use as a Witch, Most of the minions in Path of Exile 2 will reserve your spirit and will be resummoned automatically if they die. Generally you would expect to combine minions, using some as a frontline and some others to deal damage from the distance.
Some particular minions such as Clerics can also heal and revive your other Skeletons which looks very promising.
Skeletal Frost Mage & Skeletal Storm Mage
Skeletal Frost Mages and Skeletal Storm Mages are both range caster minions with great AoE, comparing them to each other Storm Mages look like a better option since they cost less spirit and Lightning Damage can Shock enemies providing more damage overall.
Skeletal Reaver
Looks like a perfect choice for a Melee oriented minion army since they can enrage, making their hits significantly stronger. Those minions are losing health so will not be consistent but can provide a very big damage burst due to rage stacking.
It is too early to say which minion combo will work the best, however it will certainly include different minion types.
Hexblast
Hexblast right now is one of the most promising Chaos skills, it can do a lot of damage and could be easily combined with Blasphemy Aura to make sure nearby enemies ALWAYS Cursed and you can use Hexblast on them in the same fashion as in POE1.
The biggest issue with current Hexblast is Cast Time - which is 1 second and can feel too high.
Detonate Dead , Unearth, and Profane Ritual
These are skills that interact with corpses - so you will need to choose between them, because they are removing corpses when used. Detonate Dead looks very promising since it has been one of the strongest low budget skills in POE1 for a VERY long time.
Currently one of the corpse related skills should be complimentary even if Detonate Dead still has potential to be a primary skill.
Enfeeble, Despair, Vulnerability
These are all curses that are here to improve our Chaos or Physical damage based on the build OR boost your survivability lowering damage of monsters (for enfeeble).
Most of the time you would need to choose one of those or two if you are going for Whispers of Doom Keystone. (Let's you apply one additional Curse)
You can also combine curses with Blasphemy to make your Curses an aura for 40 spirit reservation per curse. It could be a great idea if you have enough free spirit.
Dark Effigy
This skill can give us the Totem that will attack enemies affected by Damage Over time effects, so it can be a nice support damage source for Contagion and Essence Drain combination.
Bone Offering, Pain Offering, and Power Offering
These are mostly supportive skills for minions. Pain Offering looks like the most promising out of those for a DPS improvement for minions. Using at least 1 of those will be mandatory for Summon-based builds.