Moulded Bases - If the base is moulded onto the bottom of the figure, then it will usually need mounting on something larger to stop it perpetually falling over. This may be a group base, particularly with figure scales smaller than 25mm. I find standard card (such as that on the back of pads of lined A4 paper) adequate for 6mm or even 15mm. A stronger alternative is Mounting Board , but if you're basing something really large like a line of three 25mm figures then thin (2mm) Plywood would be advisable. Heavy gauge Plastic Card is another neat but relatively expensive alternative.

Inaccuracies in the moulding process mean that often the moulded base is not very flat underneath. To get a better fit, hold the figure over a bin and rub it up and down on a file or a bit of coarse sandpaper taped over a block of wood.

Moulded Bases - Generally I use PVA to stick figures to bases, its not the strongest glue ( Epoxy Resin would be better, but its a pain to mix it up). Super Glue makes a stronger bond than PVA, but it's very brittle, so a sharp impact, like dropping the figure, can easily break that bond altogether. PVA is weaker but more flexible. To base quickly, squirt a blob of PVA onto a number of bases, then put the figures on, rather than gluing one at time.

Moulded Bases

A moulded base stuck to another larger base will create a step, as shown here. Even after the sand texture is applied, this may still be visible. This can be dealt with in a number of ways.
Option 1: Round the step off by packing with Milliput as shown here, but this is a bit tiresome unless you happen to have some spare putty that you've mixed for something else.
Option 2: A quicker approach is to chamfer the right angled edge off the moulded base with a Scalpel, something which can be done intermittently along the edge, just to break it up a bit.
Option 3: The easiest method is to wait till the texture has dried, then add some extra blobs of PVA and more sand around the step. My basing techniques also have patches of foam flock applied at the end, which can be positioned to further disguise the step.

To stick the sand down, use an old brush to paint the base with PVA. A brush is quicker than a matchstick or similar and will give a thinner, more even coating. It is also more accurate so you will get less on the figure's feet.

When painting up to the edge of the feet, don't touch the brush down next to them, because the tip will be engorged with a big blob of glue. Instead slide the brush up to them, so the tip has less glue on it and the pressure flattens the tip. This will allow you to be more accurate.

Inaccurate: Blob on the tip	Accurate: Slide carefully up to the foot

Dip the figure in sand straight away and leave it there for a few minutes.

Not enough sand	Crisper texture

If you take it out immediately, you may not get enough sand to soak up all the glue and the resulting finish won't drybrush as well because the glue fills in the gaps and rounds out the sandy texture.