@jonassmith +1 for IceCubes.

The hardest part about getting started seems to be finding other people. If they set up their profile first (a pic, a bit of a bio, maybe some links) and do an introductory post, they're much more likely to be followed back when they start following people.

And they should follow loads of people to get started - they can always unfollow, mute retweets/boosts etc if their timeline gets too much.

I like that you can follow hashtags to get more things you enjoy in your feed