Which neighbourhoods in Munich are best suited for a young single professional? Also, what factors should I consider when choosing a place to live and what can I expect to spend on rent. I don't want to a flatshare, i'd prefer a one-bedroom. Lastly, are there any English accommodation sites that I can peruse, or is it better to hire a real estate agent?
It depends whether you're a young professional with kids or a young professional who likes to party. Areas in the city centre like Maxvorstadt and Schwabing are full of young professionals and students and have lots of night spots. See Areas and Suburbs in Munich and Accommodation in Munich for more information.
The good news is Munich has excellent public transport, so no matter where you live you should be able to get around just fine.