well, the thing about doing Gods will is, we should only worry about being good, as in - keeping Gods commandments, listening to His Church, practicing our virtues, partaking in the sacraments, praying daily, reading good catholic books daily, etc. etc.
then, how you “do” Gods will is - whatever may happen, good or bad, accept it as coming from God, be grateful, and try to deal with any situation in your life in a charitable manner.
in order to perfectly do Gods will, you need to grow in purity and holiness, which takes alot of time and effort and Gods grace, so don’t be frustrated with yourself if you do not always do Gods will now, but just be patient and work hard and let God help you now, because growing takes time, it is a gradual process,
if you are not well informed enough on the virtues and commandments and other matters of faith, then as the other poster said, get a good spiritual director, that is your best bet, someone who will be there to help you and answer your questions when you need them.
unless you are referring to what vocation God wants for you? in that case, that’s something that just takes alot of prayer and alot of alone time with God every day, and even then you don’t always know, but just keep in mind, it’s not necessarily what we do in this life that matters to God, but whether or not we did what we did with charity, so don’t worry so much about what God wants you to do as much as how He wants you to be.
so basically, we do Gods will simply by accepting all things in our life as coming from Him, and by dealing with each thing with discretion and charity, Gods will is not something to be presupposed.
ok, hope this helps, take care.