How to start responsive design

[SamohtVII]

So I have been looking into making my website responsive and just have a few questions.

 

1) How many media queries will I need to write?

I just want to cover phones and tablets and I don't want to get into too much detail besides that. Surely I can have a media query from the smallest device up until the largest phone and that will be it for phones. Same with iPads. Am I missing something here?

 

2) Can I put a media query anywhere?

I want to changes some font size when it gets too small but the media query would be random like from 490px -550px. Is this ok to do?

 

How do other people do it?

Does anyone have some set widths they use or rules they follow?

Thanks