Public Speaking - if you haven't joined a group to improve your public speaking, go to Toastmasters.org and find a club near you. People who show up at these gatherings are friendly, motivated, organized, and willing to participate - just like you. Find the next meeting, shower, dress business-wise and show up 20-minutes early.
Psychology - start with self-talk. There's always a voice in your head so you may as well interact with it. Put off things like procrastination and perfection until another day. Don't say you'll never eat another brownie, just procrastinate on it and do some stretching and pushups instead. Develop a relationship with Fear - it's there for a reason, it's an ancient part of you that knows how to survive. Appreciate and respect it. Now, realize that all humans have these same programs looping in their minds. Behavior and action are often best when handling thoughts and imagination. Instead of feeling like an outsider for the voices in your head, feel like an insider - like a participant in one of those headphone dance parties.
Business Writing - a favorite header I saw on a blog recently said: I'm writing here to learn, not to teach, so please offer feedback. Write not to teach, but to learn what you are thinking. Can you articulate your thoughts clearly? Can you convey ideas until they are accepted? ( New ideas can NOT be accepted right away. Simply because they are knew. Our brains need to bridge new concepts to old concepts else there's no way to understand them, thus we reject them. ) Next time somebody says no to you, realize they probably just don't understand. Use writing to hone this communication skill.
Accounting - open a Google Sheet right now and do a basic accounting with some basic numbers. Income, Expenses, Debts, Assets. You don't have to be precise in 5 minutes. But, get comfortable with quick access to your numbers. You'll want this business muscle to be strong as we move forward.