Before I could afford Adobe Photoshop, I used Gimp. Gimp has many similar tools as Photoshop. The UI is a bit confusing at first but after watching a tutorial, you should be good to go!
(Just a little tip in the future if you ever consider purchasing an Adobe Cloud membership for Photoshop or other programs, be sure to take advantage of the student pricing if you’re a student. Often people don’t realize there IS student pricing.)
Do not use Photoshop till you are comfortable with freeware like gimp/Adobe Xd, Adobe Xd is very easy to learn; got the hang of all the tools in 20 hours of app time. Good luck designing! 
EDIT: Thought you meant for UI Designing, for Graphics, Krita is pretty good.
Greetings, SchwarzWalde!
I saw your post on DevForum and it intrigues me a lot. I will give you some recommendations.
Freeware that helps you make design a lot is hard to find. Can you pay a little for software? I know one and it isn’t a subscription-based. It’s called Affinity Designer and has been used by a lot of designers.
I know you are going to reply to my reply saying that this is a switcharoo. So that’s why I also provide some freeware.
Adobe Xd
Adobe Xd is another designing tool similar to Affinity Designer. Adobe Xd has been used by a lot of designers worldwide. Although it does not have tools similar to Affinity Designer, it’s still enough for an ordinary designer. Adobe Xd is free and tier-based where paid tier has more perks than free tier.
Adobe Xd is not just an ordinary designing software. It is also software where you can make your prototype have motions. Also, there are plugins that make designing more easier. Adobe Xd also has application integrations where you can integrate Xd with your favorite apps.
Adobe Xd is free and available on both Windows and Mac OS X. Although it has a mobile version, you can only view projects.
Figma
Figma is another free web-based designing tool. It has features similar to Xd and Affinity Designer.
That’s all I can give. Happy designing!
Yours sincerely,
ManamiWasThere
A professional UI designer.
To add onto PurpSinister, I use Affinity Designer everyday and it works great for making logos etc. I know you have to pay 50 dollars, but this is for lifetime. Sometimes it is even on sale, I got it for 40 dollars.
Maxon: Filmmaking, Motion Design, Animation, VFX, and Editing Software You just have to apply (everybody gets approved) by filling in some basic school info then you get a 2 year license.
I would say paint.net or Adobe Photoshop Express but with Adobe Photoshop Express you have to have Windows 10 because Photoshop express only on the Windows Store for computers.
But I would say paint.net anyways because you can get it on older versions of windows (LIke Windows Vista, Windows 7 and Windows 8/8.1)
I actually stumbled upon a cool website from Reddit. I recently had to touch up some photos of mine for my Spotify artist profile.
Download some plugins for Paint.net, on it’s own it’s pretty alright but with some extra features it’s pretty decent for being free. If you’re looking for a free vector program to make logos try using inkscape.
