Other than being a husband and father the highest calling and greatest privilege of my life is serving as a ruling elder at our church. In Presbyterianism there are two types of elders -- "ruling elders" and "teaching elders". Teaching elders are typically pastors who have the primary responsibility for teaching and the sacraments (such is the case at my church where the pastor is the only teaching elder), but that doesn't mean ruling elders don't also have a responsibility to teach and promote the spiritual health of the congregation. They do, as texts like 1 Timothy 3:2 and Titus 1:9 make clear.
Both types of elders are ordained and take vows, and in the Presbyterian form of government are, in a real sense, equals. One of the reasons I like this system -- other than the fact that I believe it to be both wise and biblical -- is that it allows someone like myself with no formal theological education or experience to be selected by a congregation to serve in an ordained leadership role within the church. As I said, it's a great privilege!
Here's more on the responsibilities of a ruling elder from Carl Trueman.
Doctrinal competence is non-negotiable. It is the one major difference between qualifications for being a deacon and being an elder and it speaks clearly to the nature of the office. Elders have responsibility for the doctrinal integrity of the congregations in which they are placed. They are to be sound in life and doctrine and be able to teach. This does not necessarily mean pulpit ministry; but it does mean the ability to instruct others in the faith in some church context, as, for example Sunday school or pastoral visitation or in so [sic]
This means that the elders are [sic] have a responsibility to make sure that the minister's teaching each week is orthodox. If it is not so, and if they then fail to act, they are as culpable for the propagation of error as the minister himself.
It also means that the elders are to help ensure an environment conducive to the sound teaching of the word. This may take many forms. Most significant, I believe, is the consistent protection of the minister from hypercritical members of the congregation. This is not because the minister is above criticism but because he is always vulnerable to discouragement at the hands of cranks with assorted axes to grind. Elders should function as his bodyguard, weeding out unfair criticism and rebuking crackpots.
Because of the huge responsibility towards the church which elders carry, they are also to continue to study diligently and thus to make sure that their knowledge of theology is constantly being strengthened.
There you have it. A ruling elder should be a mix of teacher, listener, encourager, bodyguard and student.