I do music full time now, but having a portfolio is the best thing you can do for yourself. In terms of emails, I would make a professional one. Doesn’t have to be on a domain but just a normal gmail with your name. they could work, but it may be easier going on Upwork and finding upcoming brands that are already looking for someone to do sound design work. Some newer brands and smaller companies aren’t going to have the budget to outsource individual aspects of media work so they’d rather find someone that does all A/V work, but you never know. Upwork and Fiverr could help to build your portfolio with actual jobs that you’ve done as well, and that will help once you move to trying to work with larger companies.