Money can be an intensely personal thing -- which is exactly why giving to the work of Christ in the church is a good thing. It's a way to continually remember that our hearts and lives are now hidden with Christ, who gave us his all. Now, instead of feeling the excesssive need to use our money to feed our souls, we're free to invest our lives and our treasure in the things that are of eternal, redemptive significance.
If you're trying to figure out how much to give, start by remembering that the New Testament standard for giving is what Christ gave: his all. Of course, that doesn't mean you need to give us all you have. It means that what you do give, ought to include your heart. In order to do that, you should consider giving sacrificially and regularly.
The New Testament doesn't make any explicit command that you should tithe 10%, but neither does it negate that Old Testament standard. Bottom line, ten percent is a great place to start. Whatever you do give, keep the words of the Apostle Paul in mind:
"Each man should give what he has decided in his heart to give, not reluctantly or under compulsion, for God loves a cheerful giver. And God is able to make all grace abound to you, so that in all things at all times, having all that you need, you will abound in every good work."
2 Corinthians 9:7-8