Be careful about doubling "no-trumps," unless you hold a long established suit. Your adversary may have seven tricks in his long suit, and it is hard to discard from a "good all-round hand."
Spades may be doubled when weak in trumps; but, to double hearts, diamonds, or clubs, you should have some trump strength.
When doubling remember
That you show the dealer where the strength lies.
That you stand a better chance of winning the odd trick by not exposing your strength.
That when the "maker" is on your right, you have the advantage that your trumps are over his.
That when the "maker" is on your left you are at a disadvantage; his trumps are over yours.
That it is a good time to double when the odd trick wins the game for your adversaries, and does not win it for you.
That it is a poor time to double when the odd trick wins the game for you and does not win it for your adversaries.
That with a doubtful hand it is better to be satisfied with what you can make without doubling.