Tithing in essence is an act of obedience and faith.

Tithing is where we say, "God, I trust you with my finances." 

It's where we obey God's word and give back our "first fruits" 

"Honor the Lord with your wealth, with the firstfruits of all your crops." Proverbs 3:9

How much to tithe?  Traditionally, we suggest around 10% of your income.

However, if that's too much, just give what you can, and see how God shows up.