Not sure why I never heard any of the modelers mentioned this, but this is what I use. Or maybe nobody discovered this yet.
1. bamboo stick (can get it in local stationary shops or supermarket)
2. one pack of Tack-It by Fibre Castel (pre-cut preferred, can get from local stationary department)
grab a little bit of the Tack-It and paste it on the tip of the bamboo stick to make your bamboo stick little sticky on the top. You can then hold the parts and very handy for air brushing the parts.
advantage of Tack-It is it is sticky, but not that sticky that able to peel off paints or too soft that can leave left over on the parts when tried to remove it. and it holds the part firmly especially small parts that no where to find any grib to hold on.