These days I'm going to take the subject of my master. I'm wondering how to search about the subject and how to decide which master thesis I can take and work. The one option is to go to a professor and take anything that he gives me and work with if I like it. Is any other way to search about hot topics on my research area? So far, I have search on google scholar for related work on my area... Any other suggestion that I can do before decide for the subject is more than appreciated.
My advice would be to go visit not one professor, but a few. Don't ask them specifically for a thesis topic, but tell them you are looking around and ask them to talk to you about their research. Ask about weekly seminars at your department, and go listen to a few of those. Get a broad view of the different topics that groups around you are working on, then decide on something.
You should have a research methods teacher who will guide you through the process of identifying a good area of research for you.
Your thesis will take a significant amount of work and you need to consider many things. For example, what are you interested in? If you select a topic which you are not interested in then you will likely lose hope and go nowhere or do a poor job, receiving a poor mark.
Another consideration is access. This is a significant issue in research related to business management. For example, if you want to study how telecommunication companies do something specific with regards to recruitment, you need to make sure you actually have access to telecommunication company HR departments. Without that access even if you are interested, you will find yourself very frustrated, again turning in poor quality work receiving a poor mark.
Basically, you should have a teacher who will walk you through this. If you don't, you should have an adviser who can walk you through this. If you don't have that, then I would definitely take advice from @F'x and ask several professors to get some ideas and narrow it down from there.