I have a wacom intuos medium tablet and a copy of clip studio running on a decent but not top end msi gaming laptop and that's basically me set. I've been using Clip Studio since back when it was manga studio 3 for inking, and now it can do so much more, like all my colours and things, it's amazing! I still use Photoshop for lettering, but I hope in the future to not even need that step.
For my thumbnails I just use cheap sketchbooks and any old HB mechanical pencil. I always like to keep things simple when doing doodles and sketches.