Responsive design without pain
Small first
A design that starts on desktop and shrinks always produces compromises; one that starts on the phone and grows produces a clear hierarchy of importance. On a narrow screen there's no room for what isn't essential, and that's exactly the exercise every interface needs.
In practice: one column, readable typography, and touch areas large enough to tap with a thumb.
Breakpoints by content
Don't pick breakpoints by device models — the list changes every year. Widen the window until the layout starts to look bad, and put the point there.
Most modern layouts need two or three breakpoints in total. If you have seven, you're most likely drawing screens instead of defining behaviour.
What actually breaks
Wide tables, images with a fixed ratio, long Hebrew headings that split awkwardly, and menus that vanish. Each has a simple fix: declared horizontal scroll for a table, a defined aspect ratio, and controlled word breaking.
Going deeper
Check the axes people forget too: a very wide screen with lines too long to read, 200 percent zoom, and landscape on a phone. All three are more common than you'd think, and all three break on sites tested at only two widths.