I posted here with the results after the first year, and continued in subsequent years. Last year, someone asked if I was still doing it. I am, and it's working out great. The rate of giving is steadily increasing; in 2013, donations reached 1.5 times nonessential spending and 30% of income.
I have a lot of privileges that make it easy to give, but nonetheless, it's still a good thing to do, and I encourage you to consider a scheme like this if you are thinking about how you'll give to charity. With this method, you get to decide what is essential and what is non-essential, so (a) this motivates thinking about what is essential, which I find useful; and (b) it works for any income level, since spending money on things that are truly essential doesn't affect your charitable donations.
It also matters a lot which charities you give to; some charities can be massively effective and others not at all. This year my largest donations went to Deworm the World, Schistosomiasis Control Initiative, charity:water, Planned Parenthood, Partners in Health, Innovations for Poverty Action, and Village Reach. Check them out.
Do you have plans or processes that you use for giving to charity, deciding how much to give, and choosing the organizations you support?