what are the primary attributes for a good decision rule to evaluate investments?

Answer 1

If this is play money or it doesn't mean anything to you, go ahead and evaluate all you want with limited resources and little knowledge about investing.

If you want to make money, go visit a professional with a CFA, CFP, or CFS and let them invest the money for you.

If you are just getting started and want some fairly simple investing, do some index investing with ETFs.

You will get crushed or fall into dumb luck with stock investing.

Answer 2

Essentially draw up a list of requirements you have for a good investment and don't buy until you find a stock that meets your requirements. While I don't have a really explicit list, I tend to look for stocks with the following:

A strong brand or some other factor that gives the stock an advantage over competitors (often called a moat in investing.)

A stock that is selling at a discount to a reasonable estimate of its intrinsic value.

I also look for stocks that have been hammered by the market lately for a reason that doesn't throw the long term health of the company into question. For example a company that reduces forward earnings estimates will often see its stock hammered, but remain viable over the long term. Sometimes stocks simply wander downward for no reason whatsoever and create good buying opportunities.

Look for a company with a good return on equity.

A lot of cash and no debt is a plus.

A dividend is also a small plus.

Again this is just my list. GO with what works for you.