A: What is the definition of work? how do we tell we have work that produce by our faith?
B: When we have godly works, then that work will agree with the Holy Spirit who is in us. We don't know the Holy Spirit's will apart from the scriptures. Of course, there are plenty of times when we are called by the Spirit to do something good that is not specifically referred to in the scriptures. But the general idea or the principle should be in the scriptures. There would not be any "new" good works. An example of this is when Jesus was told by his disciples that they saw someone casting out demons in His name who were not from them. He was glad and said that no one can cast out demons unless the Spirit is with them. The principle is this: casting out demons is always a good work. However, this is really casting out demons and really with Jesus' authority. There is another example to contrast this in Acts. There some Jewish men saw Paul cast out demons and they tried to do the same thing in Jesus name, but they were not followers of Jesus. They tried to cheat. However, the demons said they knew Jesus, they knew Paul, but "Who are you?" And the demons beat these men up. (That is one time when I am applauding the demons.)
Also keep in mind that what the world defines as a 'good work' is not always the same as what the Bible defines as a good work.