Without grace, we fall into sin. Grace is given to all men, although not in equal amounts. Some receive more, some less. God is free to bestow His gifts as He likes. The Blessed Virgin received more than other mortals.
Christians receive more than pagans.
Those in the state of grace are likely to receive more than those in the state of mortal sin. In a way, our graces depend also on our dispositions. The principal ways of obtaining grace are prayer and the sacraments , especially the Holy Eucharist. Actual grace is obtained by good works. It is especially obtained by the use of means offered by the Church, such as offering Mass, listening to sermons, etc., and receiving the sacraments, particularly the Holy Eucharist, which contains God, the Source of Grace.