The worst task do is the writing task, whatever it is. When you have written your final draft ( read here what is a final draft )have a break. This draft will need revising another three times at least until it is in good order so it makes sense to have a rest for a while before beginning to work on your final version. You should also run a spell check on this second draft and you should review it for typos, incorrectly spelled words, incorrect punctuation, and unintentional repetition. It is also important to check the grammar at this stage. This is a step you need to be very careful with because grammar errors are not always as obvious as spelling mistakes.