10 of my favorite Android apps for
Photography, Videography, Editing:

Setup / Positioning:

Google Maps:

I think everyone's familiar with Google Maps, but I guess it's still worth mentioning as a great tool for gathering information on potential locations, street view preview etc.

Multi Clinometer:

There are many similar apps on the Play Store but this one works for me, great for when you're setting up on a tripod and want get the angles just right.

SkEye:

Astronomy app that is great for planning astrophotography or setting up for time-lapse captures that will include the Sun, Moon or Stars.

Capture:

Open Camera:

I mainly use the built-in camera (Samsung) but this one is good for a few things. I especially like the built in level.

FiLMiC Pro:

It is an expensive app but has some very special features, great for getting an idea of how the lighting / contrast will be for a shot or video as it can be hard to judge such things on small smartphone screens.

Framelapse Pro:

Can shoot a pretty good time-lapse if you are not into making your own from video files or a series of images.

Editing:

Snapseed:

I use the built-in editor mostly (Samsung) but this Google app is great for editing raw files (exposure, color balance etc) as well as normal edits.

AndroVid Pro Video Editor:

Great video editor that has many features you would expect and can also be used to make Gifs.

AirBrush:

I don't use it much but has some good options for image touch-up's especially portraits.

Bonus:

Spy Camera OS:

If you want to record while the screen is off either for stealth or just to save battery power for long recordings SCOS is a great option, also has an intervalometer like function.

Conclusion

Smartphone photography is improving at an incredible rate, but it has a long way to go to catch up to Pro cameras / sensors in terms of contrast and color accuracy; as well as bitrates / framerates for video.

I like that cell phones are starting to adopt more DSLR like features giving more control the user.

It has been said that the best camera is the one you have on you when there's an opportunity for a photo (or video) and I would tend to agree as people always have their phones on them and you never know when a great shot will present itself.

I hope you enjoyed and that these suggestions may give you some of the tools that you need to make the most of your equipment.

Thanks for stopping by!
@Ryn