Yuk! It's everyone's most hated activity: essay-writing. This post will focus on how to write the introduction, and make sure that when you start laying down track, it takes you where you want to go. When you're done, go here to get help with Writing the Conclusion to an Essay.
 First, highlight the key words in the question, like so:
How do the writers present love in these poems?
How does the poet convey intense feelings about the [subject]?
How does the writer explore the ideas of strength and weakness?
 Your first sentence should use these key words, like so:
In these poems, love is presented as...
The poet conveys intense feelings about the [subject] by...
Strength and weakness are central to the novel...
 Now focus on what's most interesting about the text in relation to the specific question asked.
If it asks about love...
Is the poem a traditional love poem? What type of love is it? Lust, or erotic love? Spiritual love? Familial love? Unconditional love? Desire for money, property, killing? Does the writer subvert conventions and expectations? Do they show different sides to this in different characters? What is the author's attitude to it - positive or negative? Are there any shifts or developments in the idea? Is it addressed to someone, and if so, how does the writer feel about them?
If you're being asked to compare texts, explain briefly, what's similar and different about the texts?
Summarise the main points as quickly and briefly as you can, like so:
Explore how love is presented in the Mercutio's Queen Mab speech and in Sonnet 130?
Both pieces are written by Shakespeare on the theme of love. One is an extract from Romeo and Juliet where Mercutio, a chaotic, mercurial character, gives a long speech about a cupid-like figure, Queen Mab. He speaks more about desire than he does about love. He describes lust for money, property, killing. When he does talk of 'love', the language is more erotic than romantic, and dirty. In Sonnet 130, Shakespeare uses his own point of view to describe his mistress, and how precious she is to him - in very down to earth language. Both use iambic pentameter and mannered, elegant structures, but subvert traditional attitudes towards love, and the way in which it is presented in late sixteenth century verse.
How does the poet convey intense feelings about [something]?
Think about the poet's feelings - positive, negative, or mixed, and does this change? What mood or atmosphere do they develop? Is there a theme? How does the poet break up their ideas; which comes first and why, which comes last and why? What mood do they leave us with?
How does Ted Hughes convey intense feelings about the fish in 'Pike'? [read more of this essay]
The poem, 'Pike', conveys the poet's intense feelings about the fish. He writes about the terrors of night fishing and about the brutality of some little ones he had as pets, which later grew out of control. It seems to be a nature poem, but this is not a romantic pastoral poem purely about the beauty and innocence of nature. This is dark, older than God, it seems terrifying where it is beautiful.
How does Rossetti convey intense feelings in 'Birthday'? [read more of this essay]
*N.B. I went straight into the essay, with minimal introduction for this example.
But what if you're writing about a novel?
For an A-grade essay, you need a strong grip on the key themes, characters and every possible way of contrasting and interpreting them - that is relevant to the question asked - before you write your introduction.
How does Steinbeck explore ideas of strength and weakness in Of Mice and Men?
Of Mice and Men explores mental, physical and moral strengths and weaknesses as portrayed in key characters. Lennie is physically strong, bear-like, but mentally weak. Crooks, Candy and Curley's wife all come from positions of weakness, and all are cruel to those below them - showing an essential weakness of character. They experience cruelty and transfer it to others weaker than themselves: Curley's Wife to Crooks, Crooks to Lennie. In places, Steinbeck challenges traditional attitudes to 'strength'; where characters abuse or exploit their power - as Curley does, and George did when he told Lennie to jump into the river in Auburn. This abuse of power is no strength. In his Nobel-prize acceptance speech, Steinbeck said that in this novel, he wanted to celebrate ‘greatness of heart and spirit’, and that 'courage, compassion and love' were the greatest strengths in the ‘endless war against weakness and despair’.