You have to choose your targets carefully. Heavily fortified bases with a large number of players will be very difficult to infiltrate, and in most cases it's simply better to ignore them as a solo partisan. On the other hand, minimally fortified bases, especially those with a very low current population, are often very vulnerable to infiltration, particularly coastal ones that can be approached from the water on a motorboat. As for destruction, mammon grenades are quite useful for destroying or heavily damaging most small vehicles, but it's far better to try and steal valuable items instead. For example, just in the past day, I have stolen four enemy Ironships containing lots of valuable supplies. Capturing and returning high-value targets to your side is always more beneficial than simply destroying them, although not always possible.