I know the word 'essay' gives people sleepless nights and hair-pulling days and while I've had my fair share of those I've had a fair bit of experience writing essays, thanks to school and uni.
I'd read a lot of tips and instructions on writing essays which are all helpful but the best method I've ever had (primarily for History essays) is the way we were taught in my history subject at high school. It allows you to structure your research logically and makes it easy to reference your essays when you write them.
First, get a lined book took take your research notes in (I decided to leave my sketchbook for more illustrations and got a different book for research). At the front, write down the assignment question and then break it down into the different things you need to consider to answer the question.
For example, one of the questions for HD1 is:
"The Romans were great builders. Describe some of the techniques and special features in evidence in their buildings. We now focus on Roman interiors and much detail on their layout, materials and richness is expected here. You should be able to provide good descriptions and examples and to comment on the Roman way of life."
If you break this question down you see some key points:
1) What are some Roman building techniques or special features of their buildings?
2) How were Roman buildings laid out?
3) What materials did they use?
4) What did the interiors look like (considering richness and detail)?
5) What was the Roman way of life?
Now you clearly know what you need to look for in your research. Write each question on the top of a page, leaving enough gaps between each to add your notes. I often like to add a more general question if I don't know much about the topic, then go into more detail from there. As you research, you might discover you need to ask other questions to clarify topics for yourself.
For example, I used these research questions among others:
1. What is the history of the Romans?
2. What characterised the Romans as a civilisation and what was their way of life like?
3. What are some well-known Roman buildings like?
4. What materials did the Romans use in building and interiors?
5. What building techniques are the Romans known for?
6. What is the typical layout of a Roman house?
7. What characterised the Roman interior?
As you research, look specifically for information that relates to these questions and write it down uon the appropriate page. Sometimes it helps to summarise useful information in your own words so you don't accidently plagarise later.
Keep a reference list at the back, giving each source a number and writing all the information you need to write a reference/bibliography list later. When you write your notes under each question include the source number for easy referencing later.
Then, when you've planned your essay and start writing, you have a summary of all the research you've done, with sources clearly marked.
This may not work for everyone but I find it keeps all my notes in a logical order (and the questions can often be used as a paragraph topic!) and stops me taking notes on something irrelevant.
Hope this helps!