It is recommended to find an agency. Appearance design has very high requirements on the proportion and view relationship of each view. Moreover, your clothing appearance may also apply for multiple similar designs in one application. These are the most important. It's best to be handled by professionals from agencies.
If you are looking for an agency, choose a relatively large agency recognized by the state. There is one on the website of the State Intellectual Property Office. Just find one that corresponds to your area.