Honesty, I find there's not a whole lot to do on it... compared to other modern tamas, that is. You take care of your tama (by feeding them and playing games with them), you can marry them off starting from the age of 5 (I think), and you can buy jewelry for some reason. That's really it. There might be more with the whole bumping thing but I only have one at the moment so I can't say anything about that specifically.
On the flipside, the Friends requires less maintenance than other tamas (not that I personally think other tamas are that needy to begin with).