Start with the parts you need, not the boards you expect to buy. Give each part a short name, then record its finished length, width, thickness, and quantity. Keep repeated parts on the same line so they are easy to count.
Next, group parts by material and thickness. Sketch how each group could fit on the stock you plan to buy. Leave room for saw kerf, trimming, and any defects you need to work around. If grain direction matters for a visible part, mark it on the sketch before cutting.
For example, a small shelf might need two sides, a top, a bottom, and one shelf. Give each part a label that matches your drawing, then mark each cut piece so the parts are easy to find during assembly.
The GGC Studios Woodworking Cut List Kit includes a stock list, cut list, and assembly sequence. https://payhip.com/b/NyhcV