Do they follow a storyline like a show would, or can I just randomly pick up from anywhere? I read Action Comic #1 online where they introduced Superman, but nothing else yet.
Yes, they follow a long storyline (or followed, before the damned reboot

) but you can understand what is happening and catch up along the way. If you want Lois & Clark's romance you can start in 1990 -
Superman V2 #43 .
The chronology is confused (there were four weekly different titles plus an extra title in months with five weeks) but you can follow it
here .
Andreia