Give where you want to give, in the manner you want to give. There is just too much joy to be found in giving not to make it part of your life. Getting is cool, becoming rich may be glorious, but appropriate giving to a need or opportunity is wonderfully satisfying.
One of our favorite gifts, right after Junior Partner Ministries and BFU, is a gift toward micro finance. Even a small gift made here can make a huge difference in a village's prospects. Notice that for me all these gifts are about the future - each makes our world a better place to live.
Don't be guided by guilt, don't let slick pictures of a need impel you action. Let your first choice be action and seek out those giving opportunities that will yield the most satisfaction in you life. Find an opportunity not just to meet a current need, those sad pictures will get plenty of donations. Instead be part of the solution. Find and support change that will continue with positive ripples throughout society.
Find a worthy cause or causes, then share in the joy and hope they help create. Make these causes your cause, become involved in the solutions they are creating. The Bible says the Lord loves a cheerful giver; find those opportunities where you can give cheerfully - and enjoy them often.
It is not your age or wealth that will make you a successful philanthropist, it is you willingness to share a bit of what you have right now. As you age and your wealth grows you will be able to share even more. Giving not from pity, not under coercion, but from a deep desire to see your gift change the world.