New Undead Player - Help

I am new to the game (in a competitive sense), and I actually had plans to main night elf, but for now, I am on undead, lol.

Basically, I keep getting dumpstered by my friend who is an orc player and I need to beat him. I have a few questions, if I could get some help:

  • When am I supposed to buy the upgrades in the Graveyard?

  • Right now, I’m spamming crypt fiends and pairing them with two statues for healing/mana. Is this okay, or should I be diversifying my army more?

  • When should I be teching my Necropolis?

  • When should I expand into a second base?

Idk exactly what kind of context the veterans need from me, but I am often playing Death Knight first, Lich second, Dark Ranger third, like maybe 5-7 ghouls on wood, I creep with the item that raises skeletons, 2 ghouls (which I replace with the ghouls on wood as they get hurt), and ultimately send ghouls back home when I have access to fiends.

My friend plays a lot of witch doctors, headhunters, Farseer, Shadow Hunter, and sometimes Blademaster. I am usually able to burst down one or two of his heroes, but his army just eats mine. I also have an issue with surviving a fight, but not having mana/HP to keep up the pressure. He also sends his Farseer wolves to kill my Acolytes a lot, I end up having to upgrade Zigs to turrets to fend them off, but it’s such bs and it pisses me off, rofl.

Anyway, if you have any more questions, I can try to clarify! Thanks in advance!

As a beginner you choose worst race to start with.
Try to play : Orc, Night Elf , Human first in that order.
Fiends are good just add some mele near, and destroyers also awesome.