It may take a long time and process to be able to sketch like professional designer sketches. Otherwise, you still have a chance to make sketches like a professional designer. Investing a good stencil set is required. The easiest technique to make a fashion sketch is by using sketchy-esque penciling. There are several steps you can take to sketch like a professional designer’s sketches.
Most of professional designer sketches have their own characteristics. You can either create your character or simply let your character show up when you practice sketching. Thus, you must get accustomed to the stencils. In sketching a fashion design, you must start by drawing the body. Then, you can continue by drawing the clothes on the body. In order to keep everything organized, it is highly suggested to have several sketchbooks.
Another alternative is you can just keep a folder for your sketches. You can learn from fashion designer sketches on how each sketch is made and how long it takes to make one fashion design. Having something to help you keeping track of your fashion designs will also help you to provide a portfolio when you want to level up your career as a future professional fashion designer.