When I started back in the hobby some 4/5 years ago now, I really underestimated the importance of basing. I thought about the model first and only, almost in isolation. As I've progressed with my hobby basing eventually became as important as the miniatures themselves.
This was not a quick realisation, my death company have OK bases, but it wasn't until I started my Dark Angels and Mechanicum that I really put a concerted effort into my basing to help make the miniatures "pop" and fit a certain theme. Bases will make your miniature look better and vice versa!
With both my Mechanicum and now my Solar Auxilia I have been doing my bases the Dave Weston way, which is to get them all done separately without the miniatures glued to them. This helps a lot with not swamping the feet of a miniature with sand or snow and letting them sit on top of the base rather than sunk into it.
The Solar Auxilia as you may have seen from my previous posts have been painted on sprue or blue tacked to a blank base. For the second squad I took some pictures to show the progression of my bases at a few stages:
Here the bases are just painted black. After this stage they were drybrushed a few grey colours for the flagstones before the surrounding bases was painted and highlighted brown, given a wash and then flock and barbed wire glued on:
Already with this you can see how much the base comes to life. Because I want mine to be properly Grimdark I then covered them in two tones of blood and washed the grass loosely to make it look muddied and browned:
And here are some picture of the Veletaris axe squad on bases like these:
I think if you design a base to fit your miniatures style and give them a proper theme you will always end up with a better looking miniature. Don't think this is me saying flocking your bases is bad! It isn't, BUT if you are striving towards the best looking miniatures you can produce as part of your hobby, as it is with mine, then I strongly suggest you take a good look at your miniatures and decide how you want them to be based BEFORE they are stuck down on a base.