Avoid an introduction which predicts what you will write about but makes little reference to the specific ideas of the text. Very general introductions often lead to very general essays which demonstrate no understanding of the text.

Which poem is this essay going to be about?

This poem explores important ideas using a variety of different techniques such as structure, words, images and sounds. The themes are powerful, the atmosphere is very strong and significant and the tone is very effective. The writer’s ideas are put across in a very convincing way which the reader can relate to.
    The structure is important as it helps the poet to show his ideas. The stanzas are organised to show a development of the poem’s ideas up until the end where the story of the poem is concluded.
    The types of words that the poet uses are very important and they are used in all the right places to create and add to the atmosphere. The atmosphere of the poem is very important and is linked to the poem’s themes.

This essay could be about any poem. It shows NO understanding of the poem the student has been asked to write about and is therefore unlikely to achieve even a grade F! The essay does constitute a useful framework which could help to structure an essay but all the specific details need to be added. What are the ideas? (about loss, childhood innocence, poverty, social injustice or ...?) What is the atmosphere? What is the tone? etc.
 

Here is another introduction which needs to be improved:

In this essay I will talk about the ways in which Charles Lamb reminisces and conveys regret in The Old Familiar Faces. I will talk about how he has very many ideas, themes, thoughts and feelings in the poem. Also I will talk about its main structure, tone and portrayal of atmosphere  Also I shall give my own viewpoint.

In this essay I will talk about the ways in which Charles Lamb reminisces and conveys regret in The Old Familiar Faces. I will talk about how he has very many ideas, themes, thoughts and feelings in the poem. Also I will talk about its main structure, tone and portrayal of atmosphere. Also I shall give my own viewpoint.

The underlined words are unnecessary and should be deleted.

Charles Lamb reminisces and conveys regret in The Old Familiar Faces. he has very many ideas, themes, thoughts and feelings in the poem. (but what are they?) …structure, tone and portrayal of atmosphere. (and why are these important?).…my own viewpoint. (which is?)

What is left now needs to be developed. Instead of just stating that there are ideas, themes etc. you need to state exactly what those themes are e.g.

Charles Lamb reminisces and conveys regret in The Old Familiar Faces. He explores ideas about friendship, loneliness and time passing. His thoughts are all of the past, of his old friends who have all "gone", and we sense his desperation; he seems to feel abandoned. The repetitive structure of the poem helps to emphasise feelings of loss and his inability to come to terms with it. The tone of the poem is mournful. He evokes the cheerful atmosphere of his youth in a way which emphasises how dismal and lonely his life now is. My own viewpoint is that this is a poignant reminder of the value of friends and how keeping in touch with friends is important.

This new version of the introduction is a much better starting point for an essay. With this introduction it would be easier to go on to give detailed analysis of language and poetic devices throughout the essay.