Introduction
George Marsh asks a four-fold question regarding spiritual gifts: (a) what are these spiritual gifts? (b) How does one receive them? (c) Are they for all believers or some (especially the gift of speaking in tongues)? (d) How can one identify his or her gift?

What are the Various Spiritual Gifts?
Altogether the Epistles makes mention of twenty one (21) spiritual gifts. In no particular order here they are:
Prophet, Prophetess or Prophecy (Rom 12:6; 1 Cor 12:10; 12:28, 29; 13: 2, 8; 14:1, 3, 4, 5, 6, 22; Eph 4:11)
Whether predictive or non-predictive, the goal of a prophetic utterance as outlined in 1 Cor 14 is primarily to instruct, strengthen, encourage, and to comfort the congregation (vv. 3, 31). Furthermore the utterance is subject to evaluation (v. 29). If predictive, failure of the utterance to come to fruition renders the utterer fake (Deut 18:22).
Evangelist (Eph 4:11)

If you have ever wondered what the portrait of an Evangelist looks like, look at Philip, one of the seven deacons in the Book of Acts and to whose name is tied to the label “Evangelist (Acts 21:8). He not only engaged the masses with his proclamation of the good news, but initiated evangelistic conversation one-on-one (Acts 8).

Pastor (Eph 4:11)

The word for Pastor in the Greek is literally a “shepherd.” In other words what a shepherd is to sheep, a pastor is to his flock. Like a shepherd the pastor displays care, offers guidance (cf. John 10:3), extends protection/security (cf., Matt 9:36), puts his life on the line for his sheep (John 10:11).

Service (Rom 12:7)

The word for service is a variation of the word “deacon.” As is well known deacons in the book of Acts offered, not received, services. They were players, not spectators, when it came to serving the church. The gift of service therefore has to do with being a participant in the process of meeting the needs of the saints/church (cf. 1 Cor 16:15; 2 Cor 9:1, 13).

Teaching (Rom 12:7)

Prophets speak the words which God reveals to them while teachers engage in the passing on of the truth of the gospel which is already the revealed truth.

Encouraging

The encourager comes in handy in challenging, low moments, in times of distress and affliction. The goal of encouragement is to inspire and to uplift. (Rom 12:8, cf. Acts 14:22; 15:32; 16:40; 20:1, 2; 1 Cor 14:31; 2 Cor 7:13; Eph 6:22; Col 2:2; 4:8; 1 Thes 2:12; 3:2, 7; 4:18; 5:11, 14; 2 Thes 2:17; 2 Tim 4:2; Titus 1:9; 2:6, 15; Heb 3:13; 10:25; 1 Pet 5:12)

Contributing to the Needs of Others

This has to do with a person sharing of what he or she owns with a needy party (Rom 12:8). This kind of sharing is mentioned at least three other times in the New Testament. The person with two tunics is urged to share with one without (Luke 3:11). As evident that the old sinful self has been shed off as a result of spiritual conversions, a thief-turned-believer is challenged to instead earn a living and share the fruit of his/her labor with those in need (Eph 4:28).

Helping Others
The single reference of the noun translated in our English Bible as “helping others” limits our discussion on this gift (1 Cor 12:28).
Leadership
This gift has in mind those who preside over, manager over, make administrative decisions over the affairs of the church (Rom 12:8, cf 1 Thes 5:12; 1 Tim 3:4, 5, 12; 5:17).
Administration
As is the case with the gift of “helping others,” the single reference of the noun translated in our English Bible as “administration” limits our discussion on this gift (1 Cor 12:28).
Showing Mercy
Most likely the gift denotes all sorts of works of mercy. This may include taking care of the sick or disadvantaged (Rom 12:8).
Celibacy
In the context of 1 Cor 7 where Paul is discussing sexual fulfillment and abstinence, it may be that the gift here should be best understood not so much as singleness but continence, i.e., the ability to refrain from sexual intercourse.
Message of Wisdom and Knowledge
These entail insights granted to the mind. They are revelatory in the sense that they include matters granted in some way or another by direct revelation (1 Cor 12:28). Granted, on this side of the Canon, the revelations must be subject to biblical scrutiny as is the case with prophetic utterance.
Faith, Healing (1 Cor 12:9), Miraculous powers (1 Cor 12:10)
We are here talking about a high degree of faith in God produced by the Holy Spirit, the effects of which manifested themselves in healings in one and in mighty works in another.
Distinguishing Between Spirits (1 Cor 12:10)
This refers to the ability to identify the source of the prophetic utterance. The ability may also include interpretation and the weighing of the prophetic content.
Speaking in different tongues and Interpretation of tongues (1 Cor 12:10f)
According to 1 Cor 14 tongues are God-directed (not audience-directed), incomprehensible to the listening ear, strictly for the edification of the speaker. For this reason, they require interpretation if they are to benefit the audience.
Apostles (1 Cor 12:28, 29; Eph 4:11)

How Can one Identify His/Her Gift
Even those who propose the use of questionnaires as a way of determining spiritual gifts are quick to point out that the questionnaires simply confirm an awareness of one’s spiritual gift. The awareness comes about through inner conviction and the testimony of outside observers.