I like adding backdrops and bases to frame photos of minis. I've had a few but, my old red sky was small and I wanted a space backdrop and an urban base.
The new backdrops were painted in dollar store canvases with cheap acrylics.
I made the urban base out of a dollar store wood frame and random bits in a bin.
The construction was pretty slapdash. This isn't diorama quality but just enough to make photos of minis feel less empty. Similarly, the paintjob is not flashy. I avoided the urge to add colorful points of interest to the base, to make sure focus stayed on the minis.
A few examples with combinations including new backdrops. 
Hell yeah square bases for Space Hulk! Always upsets me to see those minis wasted on round bases for 40k.