A colour palette in an afternoon
Start from one colour you love, and let contrast rules do the rest.
You do not need a design degree to build a palette that works. You need one colour, and some discipline.
Start with one
Pick a primary colour you would be happy to see every day. It will be your links, your buttons and the accent on every card.
Derive the rest
A darker shade for hover, a pale tint for backgrounds, and a neutral grey family for text. The theme settings can generate these from the one colour.
Check contrast
Body text needs a contrast ratio of at least 4.5:1 against its background. Test it rather than trusting your eyes on a bright screen.