Don't think of it as building a website and setting break points for different screen sizes. I used to think of it that way too.
What you want to do is think of it as building a website that doesn't break. When designing in rlm I start of with my full site. Once I am happy with the layout I start moving the slider to the left until my website "breaks" then I add a break point and adjust the content and layout to look good again. Then when I'm happy again I continue moving the slider to the left and so on and so forth.
When I get down to about the 480ish veiwport I start thinking mobile layout and what I want to see when my website is viewed on a table or smart phone. I try to hide alot of the wow galleries and videos to let my site load faster and have only pertinent information available so my clients won't have too scroll endlessly to find information.
Designing this way will help future proof your website so it will work on any screen size!
Hope this helps

Steve Kolish
www.misterwebguy.com
YouTube Channel:
https://www.youtube.com/channel/UCL8qVv … ttneYaMSJA