1. Do I have a genuine burning desire?

2. Do I have a ability to preach and teach publicly?

3. Do people get converted through my ministry?

4. Do the people of the church affirm my preaching and teaching

Some quotes:

When young fellows say that they have not made up their minds upon theology, they ought to go back to the Sunday school until they have. Pg. 41

We must try whether we can endure browbeating, weariness, slander, jeering, and hardship; and whether we can be made the offscouring of all things and be treated as nothing for Christ's sake. If we can endure all these, we have some of those points which indicate the possession of the rare qualities which should meet in a true servant of the Lord Jesus Christ. Pg. 42

A man who would succeed as a preacher would probably do right well either as a grocer or a lawyer or anything else. A really valuable minister would have excelled at anything. There is scarcely anything impossible to a man who can keep a congregation together for years, and be the means of edifying them for hundreds of consecutive Sabbaths; he must be possessed of some abilities, and be by no means a fool or ne'er do well. Jesus Christ deserves the best men to preach his cross, and not the empty headed and the siftless. Pg. 39