The only thing I really did differently was looking at the post pages and reading through the top comments. And it's my first time modding this game. I got New Vegas with updated textures and stuttering fixes and all that good stuff and it's running at 60 frames per second buttery smooth. Make sure you read every single mod description for installation instructions and also check the post's page for additional installation tips and common errors from people. Download the first 10 most popular mods for New Vegas(at least all the ones that are meant to optimize the game or to fix bugs).Get NVSE(Read and follow all installation instructions exactly as noted in the readme file.(I have lots of experience modding Skyrim special edition and Fallout 4 as well) all of my instructions below and do as much reading material as you can for each instruction. You need to make sure that you're downloading the right files and cleaning up. Just downloading and installing mods with a manager is going to give you crash to desktop most of the time.

Modding takes a lot of practice and there's a lot of techniques to master. Honestly the best thing you can do is a lot of research. I got everything running real smooth aside from neck seams which I need to go back and fix. I actually just bought and modded New Vegas for the first time yesterday.

I use mod organizer and highly recommended it.

Fallout new vegas nexus mods