In cases like this one I can really recommend you www.thefreedictionary.com for example that's what it says here: You use most or most of to talk about the majority of a group of things or people, or the largest part of something. You use most in front of a plural noun which does not have a determiner, such as 'the' or 'a', or a possessive, such as 'my' or 'our', in front of it. Most people agree that stealing is wrong. In most schools, sports are compulsory. You use most of in front of a pronoun, such as us or it, or in front of a noun which has a determiner or possessive noun in front of it. Most of them enjoy music. He used to spend most of his time in the library.

If you are talking about something general you should use "most". For example, most people like traveling. But if you mean specific group of people you should use "most of". For exampe, most of the children are good at studying.