I'm a senior majoring in accounting and management information systems.
Here is a question I answered a while back about financial statements and employee retention. In the answer that I provided at the bottom it was to assess a company's ability to pay by use of ratios. Likewise, similar accounting methods need to be understood and implemented when assessing stocks (which is where I believe Mr. Buffett was going with this).
- How do COGS, across 3 different countries, affect foreign tax credits concerning administrative bonuses in reported SGA?
- Why would a company have a stock split of 1:3 when they had five years of consecutive losses of net income?
- What are the effects of LIFO and FIFO on net income?
As we can see the severity of the questions decreases, but if you cannot answer question 3 then you should study accounting principles.
So how much is enough just to get started?
You will never have enough knowledge to start, period. You will have to continuously be learning, so start sooner than later.
However you need neither economics or accounting knowledge if you were to learn technical analysis, many doubt the workings of this technique, but in my experience it is easier to learn and practise.
A comment on @Veronica's post.
Understanding economics and accounting are fundamental. Analysis, seeing trends, and copying are instinctual human traits that helped us evolve (we are very good at pattern recognition). Taking an intro economic and accounting course at a local community college is an excellent place to start when breaking the mold of pattern-thinking. You have to be critical in understanding what elements move a company's A/R in the statement of cash flows.
Where to start:
Literally, don't stop reading. Latest edition of Kieso's Intermediate Accounting? Read it. Cover to cover. Tax policies on Section 874, 222, 534? Read it.
This is your money, do not be lazy with it.
Take a class, read a book, ask questions!
"Welcome to [the] Science [of Business], you're gonna like it here"
— Phil Plait