How do I make sure my literature essays are good?

When writing essays, it is always important to remember that understanding the question is a part of the answer. You need to read and re-read the question and understand what exactly is being asked of you. You can highlight the important bits which you think show exactly what is being asked.Secondly, use PEE. Point. Evidence. Effect. What this means is, when you make a point or assertion, be sure to back it up with literary evidence from the text or passage and give the effect of that evidence on the reader and what the writer aims to achieve by using it. For instance, take this question "How does Ferdinand Oyono use language to develop the character of Toundi in Houseboy?I would answer it like this;
To start, Oyono uses language as an efficient tool to explore the importance of structure and form to the development of Toundi’s character. The story begins at the point where the narrator has an emotional and insightful encounter with Toundi which pushes him to reflect and call himself ‘stupid’ and ‘thoughtless’. These words are harsh ones and it is worth noting that the narrator describes himself as such after only a brief interaction with a dying Toundi. This reveals Toundi’s to be regretful of his choices hence him warning the narrator who he probably sees as a younger version of himself, evident when he continually refers to the narrator as ‘brother’ ). Considering that this is the beginning of the book, suspense is created and elicits an emotional response from the readers as they try to figure out what exactly could have happened to make Toundi so regretful and ‘bitter’. The suspense created makes the entire story more impactful as it draws readers into the story and educates them about the effects of colonialism from a typical colonised African’s perspective. 
In the above answer, my point is clearly made with the appropriate evidence and effect given. Adopting this style in each paragraph of your essays should help you achieve A star worthy essays.