I love me a good siege attack! Nice Towers, nice Castle! I've run a couple of siege attack games using 2e BattleSystem rules, with 25mm-28mm figures: photo album.
I would suggest simple block painting, using brush-tipped acrylic paint pens. Follow this up with a black or brown wash. This will get your figures table-ready in no time. If you don't like the results, you can always go back and touch them up.
I paint assembly-line style, organizing figures by pose. I apply the same brush stroke on each figure group, moving from one pose to another, until they are done. I brush on Polyshades Minwax (usually some form of dark Walnut color). When that dries, I matte clear coat them.
I decorate their bases by bushing on PVA Glue, then I swirl them in colored sand mixtures. Simple, fast, and decent looking at arm's length.
I average 5 minutes of painting time, per figure, using this approach! You cannot beat that with a stick!
If you want higher quality for roughly the same amount of painting time, invest in Army Painter's Speed Paints. They are expensive, but they produce really good results, fast… Here is a video from Wyloch's Armory, on YouTube, that demonstrates how fast, effective, and decent, Army Painter Speed Paints are. I went the dark wash route, and I am winding down on my miniatures painting (1,200+ painted, less than 200 to go), so investing in the Speed Paints would be a mistake for me. If they had come out 25+ years ago, I would have gone that route completely.
I think you will be surprised at how effective this technique can be. Take a look at these Red Box injection molded plastic Cyclops figures painted in my simple, fast way. Take a look at these Gnomes and Dwarves (top and bottom of the folder): metal and plastic figures, all painted simply, quickly, and based in a straightforward easy manner. Remember, you can always go back weeks/months/years later and pretty them up, if you ever decide they are not good enough.
Painting miniatures does not need to take years to finish an army. You have more options today, than ever before. Cheers!
