Removing dust & smoke buildup but not the paint.

You mean I go through all this work to put dust on my models ..... and there's someone who wants to get rid of it !!!!!

For the unwanted dust, I use an artists fan brush. The bristles are very soft and don't hurt any of the model parts. If the model has been sealed with a dullcote or glosscote, there should really be no problem to the paint or the decals putting it in the sink and letting water clean it up.

As a smoker, I know all too well the effect it has on models. As shermanfreak states, as long as there is a sealing coat, the decals and paint will have protection from all but abraisives. To remove the smoke residue, I use a soft, "long-haired" brush with mild soap & water. If you don't want to immerse it in water to rinse, it can be held, carefully, under SLOWLY running water. I haven't experienced any damage from cleaning my models in this way (except for the occasional antenna, pitot tube, etc.)
Hope this helps.

Mild dish washing liquid, warm water and a wide (1/2 inch) soft bristle paint brush. Dip the model in the sink with the soap and water. Use the brush to lightly scrub the model. Scrub in one direction only, such as wing root to the tip or nose to tail. The soft bristles will not break off small parts, but to be sure try to work around very small items. Rinse with warm water and repeat the washing if needed. Rinse with warm water and let air dry.

Dirt Devil makes a nice set of "micro" attachments that convert your full size vacuum. Its great for cleaning models, shelves, computers, etc. And only about $7.

i use a shaving brush, and soft antistatic leather/cloth

A womans makeup brush is good for dusting and for "scrubing" if you need to wash it with soap to get old dust off.

If the model isn't sealed with a clear coat of some sort you can use a dampend brush with or without some mild soap depending on what it takes and gently wipe the surfaces, trying not to get it too wet.

Eric