How much data is "enough"?

[SheepBeast]

I'll use wifi when im at home and i wont be using my phone really heavily during the day. Some web browsing and e-mail, bit of youtube etc. no torrenting or downloading since I can wait and do that at home. No streaming music either.

Would 750MB/month be enough, do you reckon?

How much do you guys use? and how would you describe your usage?