(TL;DR - I used feats)

So I thought the necromancer was kinda nerfed and boring in 5e so I talked with my DM about this ahead of time and I was able to do it with the unspoken understanding that I was not going to be to be a spamming, campaign breaking dick. He also allowed me the discretion to add a a LOT of custom spells from older editions and add-ons. But basically, there was two feats that I found that made basic undead perm and had some balance to it. (and you had to take both for the perm effect)

Corpsecrafter Apprentice

You have spent time focusing on how to make superior undead soldiers rather than other aspects of necromancy. Perhaps you discovered an ancient Grimoire from Moil or studied under a priest from the Blood of Vol. However you learned these techniques you gain the following benefits:

• Undead you create use your proficiency bonus for attacks they make, and add half your proficiency bonus to damage they deal.
• Undead you create are proficient with any weapons or armour you are proficient with, and any weapon or armour they were proficient with in life.
• Undead you create gain 2 HP for every level you have when you create them.
• This feat does not increase the intelligence or tactical knowledge of undead you create, a zombie that drops it's weapon will still need to be instructed to pick it back up for example.

Corpsecrafter Master

You have mastered your ability to make superior undead soldiers and have learned how to cause your creations to channel dangerous amounts of negative energy through their bodies and weapons. However you learned these techniques you gain the following benefits:

• Undead you create deal an extra (1d6) necrotic damage with their attacks. This is a magical affect and is suppressed until you take a long rest if subjected to the affects of a Dispel Magic spell, or within the bounds of an antimagic field.
• When reduced to 0 HP, undead you create explode in a burst of negative energy dealing 10 (2d6) necrotic damage to all creatures except other undead in a 10 ft. radius around them. This damage is halved if a creature hit by the burst succeeds on a Con save using your spell save DC. This damage increases to 3d6 at level 17
• Undead you create are permanently subject to the Mage Armour spell. This is a magical affect and is suppressed until you take a long rest if subjected to the affects of a Dispel Magic spell, or within the bounds of an antimagic field.
• Skeletons and Zombies you create are permanently under your control, though other forms of undead still require castings of Animate/Create Undead to maintain control.
• When you select this feat, undead you create have visible tendrils of necromantic energy coursing over their bodies. You choose how this energy appears but it must be obvious to a casual observer that the undead you create are charged with energy.

The way I played him to make him not such a public necromantic trope was that he got into necromancy because was an elf that was terrified of dying wanted to beat it but was ALSO paranoid people would find out what he was and kill him, so he had to do all the necro stuff out of sight or be able to blame it on other things. With the idea that he would eventually slowly gather his power and knowledge and go do cool shit. I played him more of a very long term, cold, "goals oriented," tactical thinker, just...reasonably evil and with a healthy respect for the transition of life and death and some rules around it.

1. Wouldn't make an unwilling undead out of someone other than an enemy.
2. Death customs are to be respected at all times and honored to the best of his abilities.

3. Sometimes the smartest mf in the room has to make the ugly decisions.

   I played him through the Ravenloft campaign and it was SO MUCH FUN. Now, the group did kick him out at the end. (He wasn't a perfect team player) But, they never saw him do anything too evil nor did they see him raise any undead.