People often ask me about spelling and capital letters. Here's my advice:
- Correct spelling is very important. I know students who have lost up to 10 points in their IELTS listening tests because of spelling mistakes.
- Capital letters, on the other hand, are not important. You can write all of your answers in capitals or in lower case - it won't affect your score.
- Plurals are very important. e.g. If the question asks you to fill the gap "There are many ______", the answer could be "reasons" but not "reason".
Note: I don't recommend learning spelling rules. It's better to keep a list of your mistakes, and learn correct spellings by heart.