For dissolving thermal pastes, Goof Off is a great cleaner. Available for RM8.50 at Home-Fix in 1U. It dissolves AS5 and Ceramique into liquid within seconds and then you can just wipe it off.

The best type of brushes to use for cleaning your computer parts would be those where the bristles are made from natural(animal) hair. Synthetic materials can generate static that might prove harmful to your hardware.

If you must use a vacumn, don't touch any PCBs or circuitry with the head of the vacumn nozzle. Vacumns generate lots of ESD and shouldn't really be used, but they are super convenient.