What are the best ways to learn how to create formulas efficiently?

There are two categories of "Formulas".  I assume you are asking about formulas which do a calculation.  If you know basic Excel formulas, you will find that the Quickbase syntax is similar but more forgiving in that you can use comments and use vertical spaces to make the formulas more readable.

Here are some suggestions:

1. Bookmark this link of formula functions. https://login.quickbase.com/db/6ewwzuuj/tablereport?a=q&qid=6
   
   
2.  Pay particular attention to the IF statement as it's better than Excel in that you don't need to nest your conditions. https://login.quickbase.com/db/6ewwzuuj?a=dr&rid=75
   
   
3. Check out the resources both free and paid from The Quickbase Junkie.  Sharon's enthusiasm for al things Quickbase is infectious. https://www.quickbasejunkie.com/
   
   
4. Quickbase University. https://university.quickbase.com/ and search on formulas https://university.quickbase.com/page/galactic-appventures-on-demand?q=formulas
   
   
5. Make use of Formula Variables to make your formulas more readable. https://helpv2.quickbase.com/hc/en-us/articles/4570254813332-Formula-variables
   
   
6. Prefix a line of code with // to make a comment in the text to document your formula.

 .. and post any questions here if you get stuck.

A whole different topic is how to make formula URL buttons which will  perform actions the click of a button.  A use case would be to make a button called [Approved] which would check a checkbox and set a date to today's date and refresh the record on the screen.