Taqlid means acting according to the opinion of the jurist (mujtahid) who has all the necessary qualification to be emulated. So you do what the mujtahid's expert opinion says you should do, and refrain from what his expert opinion says you should refrain from without any research [in Islamic sources] on your part. It is as though you have placed the responsibility of your deeds squarely on his shoulders. Among the conditions which must be found in a jurist (mujtahid) who can be followed is that he must be the most learned (al-a'lam) jurist of his time and the most capable in deriving the religious laws from the appropriate sources. Now it is appropriate to clarify the following issues:
A person who does not have the ability to extract and derive the religious laws must take up taqlid of the most learned mujtahid. The deeds of such a person without taqlid or ihtiyat are null and void.
The most learned mujtahid (al-a'lam) is the most capable in deriving the religious laws from their sources.
In order to determine who is the most learned mujtahid, one must refer to the ahlul khibra (those who are sufficiently knowledgeable in Islamic jurisprudence). It is not permissible in this matter to refer to a person who has no expertise in this subject.
You can know the opinion (fatwa) of your marja' by one of the following methods:
a. By hearing the ruling from the mujtahid himself.
b. By being informed about the mujtahid's fatwa by two just men or by a reliable person.
c. By referring to the Manual of Islamic Laws (risala) of the marja' or other books of that category.
When the most erudite mujtahid has no fatwa on an issue or if it is not possible for the layman to find the opinion of his marja' when he needs it, he can then refer to another mujtahid who is the second best in the line of hierarchy of being a'lam.