Icing on the Cake
I found that one thing that boosted my confidence when job hunting was to spend a little time thinking about personal branding. I picked a color palette and fonts I liked, and used those for my portfolio, my resume, to create an email signature, and in my GitHub and LinkedIn headers. It's not at all necessary, but it's a small thing that can make you seem more polished and leave a good impression - I'd recommend it for the confidence boost alone!
Other similar things you can try:
- get fresh head shots taken (selfies can totally work, just find a clear and simple background!)
- buy a professional domain for yourself
- have some business cards printed out
Don't focus too much of your attention here, because this won't be what gets you a job. But it could be the thing that catches the hiring manager's attention and makes them take a second look at your application, or that gives you the confidence boost you need to rock your interview!