i use alcohol 96º (the one that is sold in many pharmacies to clean wounds) and a toothbrush.
I usually use a cristal jar or an old glass, put some alcohol and the miniature together ,and wait about 30 mins or so, then i use the toothbrush to clean the miniature and so on until i have all the pieces cleaned.
i use this method to clean plastic minis, it's not too aggresive and does not melt the miniature's plastic (and removes many types of glues).
For metal miniatures, i use strong solvents, a mask and a brush to take away all the paint
For the emperor!
WH40K Armies: Space Wolves 6000+ pts
Night Lords 5000+ pts
Eldar 3500+ pts
IG: Cadia 1500 +