Learn how to draw normally first
Then learn 3d+photobashing
Holy shit it speeds up fucking everything. Once you have like a kitbash library built up, you can do almost anything. Also do NOT be afraid to photobash or use 3d. Seriously. Unless you have good economy of line, or excellent brush capability, 3d blockouts and photobashing will help achieve a level of professional work without grinding out every small little detail.