Make a list of the all-time great songs. Not just the power anthems but little tunes that stick with you, the songs you hum on a long journey. Don't drop stuff from the list because it's silly or dumb. ('Sugar Sugar' by the Archies is just 3 chords but tricky to get right) Now look that list up on Chordie, give them a try.
Second, are you singing along? In many songs the chords and lyrics go together very closely, if you aren't singing you may be missing subtle timing and chord change details. You don't need to sing well. You sometimes see guys in rock bands singing to keep locked in with the song (no mike anywhere near them) or even lead guitarists making noises and singing faces as they solo. (Watchout for some rock songs where the singer and his lyrics go against the band's groove, it can sound great but then so is a movie where the car goes the wrong way down a freeway narrowly avoiding all the traffic).
Have you got drums? Not the real thing but any kind of backing track or loop? Could be a drum machine, I have a friend that uses the one on a kid's keyboard. Once you have drums you'll notice where your timing sucks and where you need to tighten your rhythmn up. Rock relys on incredibly sharp timing. You'll also find that you can strum along little mock songs to drums. After that you have to work out what you want to say with a song.
Finally playing around people. The tendency is to want to fly straight into a fast, impressive, fiddly piece. Don't. The magic effect of an audience is to make your fingers turn to rubber and stumble. Always begin with the simplest song you know the best. If you goof up laugh and pretend you did it for fun. Look at who you are playing for and involve them, they won't singalong but ask them to anyway. You may think you've made a fool of yourself with that basic song but they'll secretly think you're brilliant. Most people can't play and are in awe of those who try, even if they don't say so.
'The sound of the city seems to disappear'
