ANSWER: Beginning with your second question about fruitful spiritual gifts, there is one Scripture that gives us a general answer. In the book of Colossians Paul tells us we should live our lives worthy of our calling, "being fruitful in every good work" (Colossians 1:10). This is connected to your first question about spiritual gifts that is broadly covered in many Scriptures.
The first and most important of all the spiritual blessings is available to all truly converted Christians. This precious present is God's grace (2Corinthians 9:14, see also Ephesians 2:8).
Because of conversion and grace, God uses the individuality of each person in order to impart spiritual gifts, skills, or aptitudes. They do not have to be great qualities, as humans would view them, but God sees them with the perspective of the Master Builder.
For I wish that all men might be even as myself. But each one has his own gift from God; one is this way, and another is that way (1Corinthians 7:7, HBFV throughout).
God's grace should manifest in the believer spiritual or 'fruitful' abilities. Paul states these are, "love, joy, peace, long-suffering, kindness, goodness, faith, meekness, self-control; against such things there is no law" (Galatians 5:22 - 23). When you read these verses, you will notice that love is first on this spiritual list.
Love, then, is the greatest thing God can give and is the result of his work in a Christian. Without it, everything else is to no avail.
The spiritual fruits or gifts of God, with love at the head of them all, are also labeled the "gift of righteousness" in Romans 5 verse 17.
Combining the spiritual gifts listed in 1Corinthians 12, Ephesians 4 and Romans 12 produces the following list of fruits generated by God's Holy Spirit within a person.
A person can be spiritually blessed to organize projects and lead others, to teach and encourage others in the Bible, to discern spirits, to evangelize, to have extraordinary faith or generosity, or be able to heal others.
Christians can also be spiritually gifted to be dedicated to helping others (the ministry), to interpret or speak messages in different languages, to work miracles or to speak prophetically. Christians may receive power to be extra merciful with others, or the gifts to be knowledgeable and wise on particular topics.
No matter what spiritual gifts a Christian is given, it should always be remembered that God gives them so that they can be used to serve others. They should never be used to increase our own ego or to look better in the eyes of other people.