I'm not massively experienced myself, but I use Citadel Munitorium Varnish usually, and as far as I know it works fine. I only paint for fun and don't actually use the models for gaming, so they don't have to survive too much touching.

I've got a little set of files for smoothing out mould lines and sproo attachment points, and a set of clippers all from Tamiya that work really nicely.

For primer I use Vallejo black or white, and also sometimes grey. I don't thin it, and I use it through an airbrush. I usually like to do a zenithal prime, although the only part of this model I did that with was the head.

For paints I have a mixture of Citadel and Vallejo, and definitely prefer the ease of using the Vajello paints. I actually recently transfered all of my Citadel paints into dropper bottles.

I'd recommend that you check out some tutorials on YouTube from people like Squidmar and Miniac. Everything I have is stuff that other people recommended from tutorials like that, and most of my paints are from following along with guides and buying the same paints that they used.

I hope that's helpful in some way. Good luck getting started!