Der Muslim, der auf Grund seiner Unwissenheit den Wissenden folg, ohne selbst verstehen zu müssen, der ist der Muqallid. In der Praxis folgt der Muqallid einem Madhhab (Rehtsschule). Fast alle Muslime sollten als Muqalliduun (Pl.von Muqallid) verpflichtet fühlen, doch bilden sich immer mehr von ihnen ein, das sie doch nicht blöd sind und "blind folgen" werden, sondern vielmehr selbst entscheiden was ricjhtig und falsch ist, ohne die Voraussetzungen zu erfüllen.

Difference between Mujtahid & Muqallid  (http://members.tripod.com/alislaah4/taqleed/id20.htm)
Everyone can claim to form an opinion immaterial whether it is correct or not. But that person whose opinion is acceptable and relied upon in Shariat is known as a mujtahid (one who practices ijtihaad) and a mustambit (One who has the ability to derive masaaîI from the Nusoos)?
One whose opinion is not acceptable and relied upon in Shariat is known as a muqallid (one who accepts the interpretation of a mujtahid in these masaaîI). In both these type of masaaîI (the third and fourth) it is necessary for a mujtahid to practice ijtihaad and for a muqallids to make taqleed.
 

•     Refer conditions of making ijtihaad at the end.

If a mujtahid has to err then too he will be rewarded. If his ijtihaad is correct then he will get double the reward as stated in Bukhari Shareef. Vol. 2 Page 1092.

Why should Taqleed be made of one of the four Imams only ?
One question arises here that there were many Mujiahids among the Sahaaba (one who saw RasulluIIah (SallAllahu Alayhi Wasallam) with Imaan and then died with Imaan), Tabeien (one who saw a Sahaabi in the state of Imaan and then died with Imaan) and Tabé Tabeien (one who saw a Tabeie with lmaan and died with lmaan) then why should we make Taqleed of one of the four Imams only namely:
Imam Abu Hanifa (rahmatullah alay) (born 80- AH)
Imam Malik (rahmatullah Alayhi) (born 95-AH)
Imam Shafi(rahmatullah alayhi)(Born 150 AH.)
And imam Ahmed bin Hambal (rahmatullah alay) (born 164 AH.)
What is wrong if we make Taqleed of one of the Sahaaba (Radiallahu anhum) as many virtues of the Sahaaba (RadiAllahu Anhum) have been related in the Ahaadith.

The reply to this question is that the Sahaaba (RadiAllahu Anhum) ore definitely far more superior to the four Imams. Taqleed is made of the four Imams, not because they are superior to the Sahaaba (RadiAllahu Anhum) but because it is necessary for us to have knowledge of those masaaîI in which Taqleed is made. And today the detail with which the masaaîI of the matha'hib of the four Imams has been formulated in a regulated and compiled form, the math'hab of any Sahaabi, Tabeie or Tabé Tabeie Is not found. MasaaîI from Kitabut Tahaarat till Kltaabul Faraaiz (laws of inheritance) have been collected in the matha'hib of the four Imams covering all the aspects of life in principle and in detail whether it be beliefs, Ibaadaat, dealings or community life.

In short every masâla regarding all the aspects of life has been registered. Answers to all questions could be obtained either in a specific form or in a deduced form based on principles, thereby obligating the need to refer to an external source. This, all-embracing quality by an act of Allah Taâla is found existing in only the four Matha'hib.

How can we then leave making Taqleed of one of the four Imams and make taqleed of someone else?

Allah Taâla had given in detail the knowledge of the Quraan-e-Kareem and Ahaadith to the four Imams. They were also given the necessary qualifications and ability to make ijtihaad.

They had knowledge of all the Ahaadith of Rasulullah (sallAllahu Alayhi Wasallam) that spread throughout the world through the Sahaaba Kiraam.

It is possible that one Imam may not have knowledge of a certain Hadiith and another Imam has knowledge of it, but it is not possible that none of the four Imams had knowledge of a particular Hadiith. Shah Waliullah Muhaddith Dehalwi (rahmatullah alay) writes on page six in his commentary on Muwaata Imaam Malik: “The four Imams are such that their knowledge has encompassed the whole world. And they are Imam Abu Hanifa (rahmatullah alay), Imam Malik (rahmatullah alay), Imam Shafi (rahmatullah alay), and Imam Ahmed bin Hambal (rahmatullah alay)