The most prominent way to critically analyze William Blake's poem "The Tyger" is to examine the messages and questions which Blake poses in the poem.
For example, the most prominent question (which remains unanswered by Blake) is how could God, the all-perfect and creator of goodness and innocence, have created a creature which is seen as violent and evil?
The poem, therefore, is meant to raise awareness of a reader in regards to God's thoughts and reasoning behind his creation of the different animals on earth. While the poem specifically speaks to the creation of the Tyger, one can easily come to question the creation of disease, natural disasters, and other "evil" things as well.
Basically, Blake is wanting readers to see why things exist as they do. He wants readers to question life. He wants them to think about things instead of simply accepting them based solely upon blind faith.