What is the best way to avoid ransomware while using VPN on a public network?

Hello all, got a letter of approval from the council today regarding renovations on the building I'm living in. I expect I'll be working out of home quite a bit using local networks at public libraries/cafes and such. Anyone know if VPN security differs on public networks compared to private ones? I really don't want to end up downloading ransomware or something similar. Thanks in advance.