Best is to learn how to write indicators first, will let you see the magnitude of the trading challenge. The you can either write an EA to suit your style or trade manually. Yes you can do it, it just takes time.
Trading is based on psychology. Before you begin to look for an EA ( Almost 99.99% work for a limited time but when there is a loss then you can consider there is a margin call ) and for indicators ( If bad interpretation then huge losses) , i simply advice you to begin reading the books of John Murphy ( Technical analysis of the financial markets ). After you read this book, you should be curious and push your investigations towards other fields.