Paul Lamford's (100 Backgammon Puzzles) concise cube advice is effective, simple and easy to remember. Paul uses the acronym PRAT as a guide to doubling and accepting:
PRAT stands for - Position, Race and Threats

Paul recommends doubling when you have an advantage in two of these three areas. If you have a clear advantage in all 3, then your opponents should pass.

The method itself is not that much good to a real beginner however as you still need to know if your position is in fact better and still need to know if you have any threats and what they are. For those with a reasonable understanding of the game it can help a long way. It isn't perfect as there are some positions where other factors override the result of the method, particular prime vs prime positions.

Just to illustrate things let's see the guidelines in action.
Red on roll, cube action

pip count red: 132 blue: 150 score 0-0/3 cube value (1)

Position (red) better board, high anchor
Race (red) 18 pips ahead and on roll
Threats (red) positioned well to make the bar or 4 point

From the above we gather that red has the better Position, is ahead in the Race and Threatens to make the bar or 4 point.

So if we use the criteria that 3 areas in your favor should be double / pass, then the correct cube action must be double / pass. Snowie agrees.
1. Double, pass 1,000
2. No double 0,920 (-0,080)
3. Double, take 1,210 (+0,210)

How about this one.
Red on roll, cube action

pip count red: 148 blue: 143 score 1-1/3 cube value (1)

Position (red) better board, 11 point
Race (blue) red trails by 5 pips
Threats (red) pointing on the 5 point, hitting on 21, 2 checkers up

So red has 2 out of the 3 areas which according to the general rule is a double / take.
Snowie says:
1. Double, take 0,732
2. No double 0,666 (-0,067)
3. Double, pass 1,000 (+0,268)
Proper cube action: Double, take

Last but not least.
Red on roll, cube action

pip count red: 113 blue: 108 score 0-0/5 cube value (1)

Position (red) clearly has the better board and remains flexible
Race (blue) red trailing by 5 pips
Threats (red) numerous: covering, hitting, escaping etc.

So what we have here is 2 out of 3 of the areas so according to the guideline this is a double/take right?

1. Double, pass 1,000
2. No double 0,731 (-0,269)
3. Double, take 1,151 (+0,151)
Proper cube action: Double, pass

Wrong!

This is why you should only use it as a general guideline. Here the position and threats are so great that they override the small pip deficit. Gammon is another factor and blue is so inflexible with buried checkers and ...etc etc. If you are going to use the method then look out for positions
where one area clearly overrides the others.

Also beware that not all "good in all 3 areas" are double / passes. They may not even be doubles of course as you may well be too good to double.