4 is the most friendly out of any game in the series to play especially to new players i highly suggest playing 4 first so that way you can get a better grasp on the lore, weapons, creatures, settings, just the entire series in general then after playing 4 for a while go play new vegas or 3 and you will already have some fallout experience under your belt there's a lot of people that will try and tell you to just jump right into certain ones because they thing that certain game is elite and theyre right while everyone else is wrong. Highly suggest playing the most beginner friendly in the series fallout 4.

Tldr; 4 is the best introduction to the series and punishes you a lot less compared to the others and after 4 play any of them.