When I was a child I remember a preacher saying in order to get to heaven we have to live a righteous life. To understand what righteousness is read Romans and also read my blog post Living through the Lord our Righteousness to understand what it is not.
(Matt. 6:33-34) 33 But seek first the kingdom of God and His righteousness, and all these things shall be added to you. 34 Therefore do not worry about tomorrow, for tomorrow will worry about its own things. Sufficient for the day is its own trouble.