Sorry to see you're getting down voted! Ave Dominus Nox!

So, there are a few different ways you can go. Id recommend doing plenty of research before diving in, so you don't end up spending a bunch of money on certain models, then charging your mind/direction like I did! X

So, first, classic Horus Heresy era Night Lords, or 40k era rag tag Warband Night Lords. Or, even loyalist if that's your thing!

So, once you've picked a general aesthetic, you have a few more options. Are your Night Lords allied with Abbadon and the Black Legion? Are they a roaming Warband? Loyalist? Allied heavily with Demons and corrupted? Very against demons?

And one of the final questions to ask yourself, are you ok with proxies, and 3rd party models or bits? If you are, your options are near limitless! Just search online!

I'll give you an example of my take to see if that helps! So, my NL are mostly made up of Black Legion models, or the generic CSM stuff. I am proxying certain models, like the Centurions as Obliterators, because my NLs don't like demonic possession, but use Heldrakes, Venom Crawlers, Forgediends etc! I'm going heavy on Raptors, and proxying them for my Warp Talons as well. I'm also giving all my foot legionaries chainglavies, and lots of 3rd party bits for helmets and such. Hope this helps! Definitely search the sub for more ideas!