A graphic designer or a marketing agency who employs graphic designers. It really depends on your needs and budget which way you go. You’re talking to the former right now. Feel free to DM me details, and if I can’t help, I’d be happy to point you to someone who can.

If you’re not changing your business name and are just changing the look and feel, figure out what you want it to become first before doing anything else. Hire a professional to help you if you don’t have identity design skills. Even if you do, still consider it since an objective viewpoint will help. Once you know what your new branding is, then you could hype it up before the reveal. Try to get people excited about the change. Reveal it a little at a time as a teaser and then end by unveiling it with your new logo, site design, etc.