However, as I've moved away from GW and gone on to explore other companies and other product ranges, that approach had real limits. Many models out there include little platforms on which the mini stands, and it looks terrible to just throw sand over it, as you end up with a lot of sharp angles... which don't look great. I may advocate for simple hobbying, but I do have some standards.
The solution, for me, has been Vallejo paste.
I picked my tub up from Amazon, but they do have an actual website. Since the overwhelming majority of my miniaturess have sandy bases, I've been using their White Pumice paste, but they have stuff to mimic asphalt, desert, lava... all sorts of cool things.
So let's hope into it, shall we? To base with this paste, you'll need:
1) A model
2) A base
3) Tub of the paste
4) A tool
6) Q-tip or old brush
7) Paper towel or toilet paper
1 & 2: The Model and the Base
Pretty simple. Take whatever model you have, and whatever base you want it to have in the end, and get them glued together with your normal hobby glue.
Here on the left I have a few examples of the kind of models that go really well with this basing technique, as each of them has its own inherent base as part of the existing mini. From Warlord Games, we have two horses from the Praetorian Guard box sets (each on 25x50mm bases), and from Reaper Miniatures, we have a minotaur (on a 40mm square) and a gnome (on 20mm square). The gnome had a base roughly half the size of the minotaur base... so I trimmed it down to a more reasonable size.
Whatever base you need your mini on, this is what you're going for. The model glued to a bigger base, with some space to work with.
3 & 4: The Tub and Tool
Also pretty simple. Get your tub of paste, and some kind of tool.
The tool itself isn't that important. I was really getting into sculpting for my armies a few years ago, and had a bag of tools for working with milliput and green stuff. When I went to use the paste, I tried a few, and found that I liked ones that resembled flat head screwdrivers, as the flat bit made for a good scooper, in addition to being able to smooth out the paste a little. If you are really cheap, you probably could use a small flat head screwdriver.. but a bag of sculpting tools is not hard to come by, and you may be able to find even cheaper alternatives at your local art, craft, or hobby shop.
So, when you have all these 4 things mentioned above, you can just jump right in.
Use the tool to scoop out the wet paste, and spread it around the base. As the paste dries, it generally shrinks a bit, so be sure to apply a little extra around the model's inherent base, so that the join from model-to-base is camouflaged a bit.
To the left is an "in-process" picture. Nothing complicated was really done here. I used the tool pictured above to scoop out some paste, and then spread it around the bases.
Cleanup & Drying
Once you're done, wipe your applicator tool clean with a wet piece of paper, or rinse it under the sink. If you don't, the paste dries on the tool, and will make your life harder should you ever want to use that tool again for anything.
I have an office job, so I will generally do this in the evening, and let it sit over night, or if I'm working with a single mini and want to hobby on it later that day. I apply the paste quick in the morning and let it dry while I'm at work. Drying time really only takes a few hours though, so my process is a little overkill.
After Basing... on to Painting!
Once you're happy with your basing, prime the model, and then you're ready to start painting. The paste part will need to be painted up along with the rest of the mini, but it's not that onerous.
The Optional Parts
Should you slop the paste around where it is not wanted, assemble those optional items!
Here, we have a very packed base of Roman models. Quarters were tight, and I slopped paste all over these poor guys.
The paste is water soluble, so using the water and old brush/q-tip, you can apply the water and then then either wipe the excess away with the brush, or with some paper product. I usually opted for an old brush, as it allowed me to be a little more dexterous and precise with what I was trying to remove on the models. For the edges of bases though, a chunk of paper towel is probably best.
The water and wipe approach was done here on these Romans. You will notice that there is still some paste residue on the minis. That's fine. So long as you get the gritty particles wiped off, a little white splotch here or there is just fine, and will be covered up by the primer and future painting. What you're concerned with is removing the gritty bits.
Should you not notice an "oops" until later after everything has dried, don't worry. The dried paste likes to adhere to itself more than to another surface, so you can pick and scrape away pieces of dried excess paint with a hobby knife or something.
...And there you have it. The four example models up in the top of the post took me about 10 minutes to get through - this process is not rocket science. Should you find yourself working with models with inherent bases, give the paste a try.