The following is a list of sensible guidelines to following when incorporating responsive design into your projects
When determining which breakpoints to use, always start with the recommended breakpoints and then add others on an as needed basis
Use EMs (or REMs) to make you text size scalable
Use Percentages or EMs/REMs for Horizontal measurements
Consider using EMs/REMs to dynamically adjust padding if to optimize readability of your content at different widths
Consider using relative measures for left and right margins they change in proportion to the width of the containing element
Use pixels (absolute measurement) for height/margins/paddings if you do not want those measurements to change relative to screen size
These rules are not absolute but having a standard approach speeds up development