The exception to the trump lead is when the weaker of the two trump hands contains a short suit and can ruff; then, before leading trumps, allow the weak hand to trump your losing cards.
Unless a cross ruff can be established, it is usually bad play to weaken your strong trump hand by forcing it to ruff. If you do this, you will find it difficult to exhaust trumps from the adversaries' hands and to make any commanding suit cards you may hold.
If your adversary has doubled, be cautious about leading trumps. It is good play to lead through the doubling hand; but bad play to lead up to it.
THE NON-DEALER'S PLAY OF A "NO-TRUMP" HAND
With a declared trump you aim to make your high cards; but at no-trump the high cards take care of themselves and you must try to establish your small cards.
If you are the leader at "no-trump," open your longest suit. Save the high cards of your other suits for re-entry and try to establish the small cards of your long suit.
Don't lead your aces and kings to take a look at dummy; later in the hand you will need them to get the lead and bring in your established suit. The majority of "no-trump" makes are strong in three suits. Your long suits may be the weak spot in the dealer's hand.
Try to infer, from the dummy hand and your own, the high cards the dealer must hold to have declared "no-trump." You will be surprised to find how many times an inference thus drawn will enable you to play your hand to advantage.
Having started your long suit, usually the best play is to continue that suit until it becomes established, especially if you hold one or two re-entry cards.
Don't change suits unless your suit is hopelessly against you. When it requires two leads to clear your suit, and you hold no cards of re-entry, abandon it and play for your partner's suit—the suit that he has shown by his discard, or the suit which must be his, judging from your own and the dummy hand.