i used to play someone who's been around since the sixties, and i did skip their silver age stuff. well, to be accurate, i tried reading it, but got tired about twelve issues in and wasn't getting anything important to their history, personality, or voice.

that said, i read as much of the 70s and 80s stuff as i could find, but i tend to find the bronze age a lot more fun than the silver age, even if it can get really wordy sometimes. i also read more summaries than actual comics from the 90s, 90s marvel was a harsh place.

i would definitely recommend reading about the last ten years worth of what is relevant to your character, and major storylines, but also the storylines that interest you. there are a lot of things where you can get by just reading summaries, but summaries can also let you know about things you might actually want to read! some of it, you can fill yourself in on as you go, you don't need to know every little thing before you start playing.

as long as you've got a good foundation for their character, it's okay to play a little loose with comics characters who have been around a long time. the professional writers absolutely do.