You said you’re interested in building furniture. There are “standard” sizes for furniture. And although we can deviate from standard a little bit, you can go wrong fast if you move too far from standard.
Examples: Standard height for a dining table is 30”. All coffee tables are usually within 2” of the same height. Same with chair seat height, etc, etc.
So, when making furniture, the primary decisions involve choosing your design and choosing the type wood you want to use.
You said above simple furniture. You might find some ideas if you search your new piece by name on Pinterest.
If you don't have time to do it right the first time, when will you have time to do it over?