What are the different ways of protecting one's practice? I am mindful of my skandas, but that doesn't prevent other's samsaric action, trying to influence me and my practice. What are the different ways of protecting one's practice?
Mindfulness will "protect" your practice. 

Mindfulness is a wholesome mental factor (cetasika) and when it is present, one is not reacting to phenomena, i.e. by running away from unpleasant phenomena and running after pleasant phenomena. Instead one is standing still. One is in the present moment, clearly recognizing that it is our own reactions to phenomena that create suffering. An unwholesome thought or anger is still just a thought and a feeling. Its our own aversion towards these objects, that create our suffering.

So by keeping mindfulness at all times, one is protecting ones practice. 

I would recommend the video "How Mindfulness Creates Understanding (The Buddhist TV)" by Ven. Yuttadhammo.