The below is an example of the process I go through when designing a group or line.
1: trend research to get my theme of the core trends. This usually includes Europe shopping trips, or during covid days a lot of online and local shopping.
2: Create Mood Boards, which include not only trend, but key fabrics/ yarns, color, pattern, and graphics
3: Designs
4: CADS and Tech packs
I have worked through this entire process on my own when starting a department. And also directed departments of designers through the process, usually taking care of the 1st 2 steps and letting creatively directing them through the last 2.