We please the Lord by doing his will. It basically means following the 10 commandments and being faithful in our vocation. We must always pray and discern His will.
However, this is not a ‘pay me back’ relationship. We don’t do things in order to get stuff from God, but do them because of love. Even if the motive is imperfect (wanting something from Him), we must always have the higher goal (love) in mind. We must never threat him like a vending machine. Sometimes very faithful and devout people do not receive desired healing. It is God’s will, we can only guess why. But we must trust that He does what is best for us, even if we can’t see it clearly at the given moment.
The way I seek healing from Him is that I pray for that intention. I pray the Rosary and the Divine Mercy chaplet often. Before I start I say my intention and all the prayers are aimed to that. Also, when I go to mass I put that intention forward before the consacration of the host, and/or pray for that intention after communion. Going to adoration of the Blessed Sacrament has been extremely healing for me.
Hope this helps.