What are the best free softwares needed to make a 3D game on Unity?

I am trying to learn to make my first game in Unity. I have Blender for 3D modelling and I have Logic Pro X, in case i want to make some game music. However I don’t have anything for the game art (Backgrounds, skyboxes etc., should i get round to making my own.) I want to keep costs to a minimum, and so i’m not buying Photoshop or anything like that.
So I was wondering what is the best free software for that, and if there is any other software i would need.

Cheers

Gimp! Haha, I use Gimp for making textures for my Blender models, for Unity shapes, as well as UI (raw) images. It does take a bit of a learning to it, similarly to Blender, but it’s not bad if you just dive into it. If you do need to rescale, just open a new page and copy and paste into the new one. It’s absolutely amazing!

I have never used Logic Pro X before. I usually just use my recording program that’s preinstalled and hook up my instruments into the computer. There are other programs beside Gimp, but I usually find them harder to save and find in the future.