Data usage, is 500MB enough for me?

I have been saving up for a smartphone, and am now ready to purchase one. I wastn sure what plan to use so I have been looking through a brochure, the one that seems most suitable for me is the 500MB of data per month. it will come will unlimited facebook, myspace and twitter. I would only use the data part for googling a few times a week, checking email a few times a weeks, and maybe some youtube videos, maybe some apps.. I don't know if it even uses data for the apps, its a samsung powered by android. Anyway, if you have a data plan, can u tell me how much you have, and how much of it you use, and if you think 500 MB will be enough for me? Thanks for any answers of insight.