Where to start?

I decided to start my learning with the internet as it is something i am comfortable with and can obtain information instantly without much effort. As a start to my learning i did a quick google search of 'Basic mechanical systems' to see if i could get a good overall look at the subject to see what i am dealing with. 

initially this was rather unsuccessful (google gave me results of anything remotely related to mechanical system, and sometimes completely unrelated) however once i refined my search down  and reworded my search (Design and technology mechanical systems etc.) i  had more specific results. The internet can be a great source for information but can more often than not produce unrelated results and send you off into a tangent. If you know how to search effectively or know good reliable reputable sources it can be an absolute asset. 

initial Google search results when typed 'mechanical systems'

As i was searching on the internet i starting thinking about the following points;

• Do i pull out 1 or 2 aspects of mechanical systems or look at the subject as a whole? The subject seems rather extensive and  i am thinking it would be best to look at the principles of the subject which would give a good overal understanding as i could probably spend a lifetime becoming an expert in mechanical systems. I have found that there is also no one definition of mechanical systems, it cant be summed up very easily. 
• If i do take just a few aspects of the subject, how do i know what is the most important bits? As i said above i need to understand the outlines/principles of the subject giving myself a good foundation of knowledge to work up from. I guess i wont know the answer to this question fully until i get further into my research or indeed the end of this module.