That's right! The software that professional photographers use for their photos, also has an app version - and it's free! Without being biased, this app has all the main settings you'll need, and because it's made by the same people who made Photoshop, you won't lose photo quality, no matter how much you mess about with the settings. (Android & iOS)
This app only lets you do one thing, but it's something that will definitely make your selfies stand out. This app allows you to add a gradual blur in the background of your photos, so that you stand out from it, giving your photo that 50mm-lens look. It's easy to use, it's free and the blur looks realistic, as if you've used a professional camera. (Android & iOS)
Even though this app is known for being in the Social Media category, it recently updated its editing side, and it turns out that the editing side is actually very good. This app is great for your basic settings, such as brightness and contrast, as well as advanced settings like tilt-shift, blur and HDR, which are usually used in professional software. However, Instagram forces you to crop your photo square, which is bad because you can't always fit a photo into a square. (Android & iOS)
This app is the one I use most with my selfies because it has some great retouching tools, such as being able to remove spots, which is a big deal for spotty people like me. While the basic settings like brightness and contrast, aren't great, this app has a lot of cool tools for you to make your selfies stand out. Also, what's great about this app is that you can download borders, overlays, etc. straight from the app if you're connected to the internet. (Android & iOS)
This is the kind of app that does what it says on the tin, and it just works. Retro is now very popular, especially with portrait, and out of all the apps I've tried, this does the job better. It's also good at keeping picture quality, which is always a good thing. Try it out and see what you think. (Android only)
Tip: If you keep saving and opening the same photo file in different apps, you photo will lose quality. This is because photos are saved in JPEG, which is a compressed version of a photo. So, I recommend only editing each selfie in one app.