Others have made good suggestions. I think it just depends on what you find to be interesting, you can really do whatever you want.
I said this elsewhere but I just made a random tester sim to explore back when I basically just had the base game (which I think I got with Dine Out and Spa Day) whose descendants are still in my game because I got interested in having a slow legacy/rotation with a bunch of characters.
In previous versions of the game, I did random different things depending on what interested me. Sometimes I played with celebrities, sometimes it was epic family play, one time it was a horse farm, then there were other random households that I played until I got bored or wanted to do something else. I like the way that I am playing now because my own sims keep running into each other.
I think my new rule is that most dramatic action will require sims of mine to randomly run into each other. They aren't going to meet new sims unless those sims actually physically walk by or they actually meet them somewhere. Want to make a friend? Who is walking by? Pick someone. I won't force anything to happen but any plots that happen will be based on that. I might break that rule if the result is entertaining though.
You could pick one of the packs and decide to base a household around it or you could use that story generation tool when making a new sim. Answer some questions, get a random sim and figure out how to play them. If they get boring, make a new one. Eventually you'll get interested in something. Leave the random sims in the game because if you don't play them, they will be like townies and you will see them around.