What is your level in English? No one but you really knows what you are capable of doing, so the best way to determine your level in English is to go to :
Answer the questions honestly and you will have a good idea of your level in the four skills:
Reading, Writing, Listening and Speaking. When preparing a CV, use the European standards to designate your level.
How do you improve your level? Your level in Writing depends upon your level in Reading. If you read frequently, choosing texts that are easy to read, your level will improve and your Writing will improve. If you listen often to songs in English and to films in VO, your speaking will improve.
The secret to learning a language? Comprehensible input. Which means listening to and reading things that you understand at least 90% of. When teachers ask you to produce, that is to speak and to write, we are measuring what you have learned, but we are not teaching.