The saints pray for us in two ways. First, in Heaven, they pray for us--intercede on our behalf--to God. Second, and less obviously, they pray for us: they teach us how to pray through the prayers they left behind. To develop a more serious prayer life, start collecting these gems.
At the very least, if you kneel down to pray and can’t think of anything to say, the saints will teach you what you should be saying. (Warning: this is humbling. You will realize how far from holiness you really are... not a pleasant experience.)
The best-known saint’s prayer is probably that of St. Francis of Assisi (“Lord, make me an instrument of your peace…”). Here is one by St. Thomas More that you probably haven’t seen:
Give us, Lord, a humble, quiet, peaceable, patient, tender, and charitable mind, and in all our thoughts, words, and deeds a taste of the Holy Spirit.
Give us, Lord, a lively faith, a firm hope, a fervent charity, a love of you.
Take from us all lukewarmness in meditation, dullness in prayer.
Give us fervor and delight in thinking of you and your grace, your tender compassion towards us.
The things we pray for, good Lord, give us the grace to labor for, through Jesus Christ our Lord. Amen.
I particularly love this prayer because in it, St. Thomas was asking for all the gifts that we also need: humility, patience, fervor. Those are difficult virtues to acquire. I don’t find it terribly hard to avoid lying, cheating, stealing, or getting drunk, but being humble, quiet, peaceable, patient, tender, and charitable is another thing altogether. So it’s comforting to know that St. Thomas struggled, too.