I, Cliff, was disappointed with my play on this hand, where I went one off in 4S.
East opened 1H, West raised to 2H and South finally played in 4S.

West led the H4, and East played the HK. South needs to think carefully about his plan, at trick 1.

There are 3 obvious losers - a heart a diamond and a spade. What are other dangers?
A 4-1 trump split will need careful play, but the main danger is a singleton diamond, since N/S have 9 diamonds.
If West had a singleton diamond he would probably have led it, so Declarer should think about East having a singleton diamond.

Initially, it seems that Declarer must tackle trumps as soon as he wins the lead, but he needs to think further. For his opening bid, East must have at least one of the missing aces, and he could have both. If East has a singleton small diamond, he will be able to get a ruff, however Declarer plays. However, if East has the singleton DA, then Declarer must prevent West gaining the lead after the DA is played.

If East wins trick 1, and he has the singleton DA, he will cash it. Then if West has the SA, East will get a ruff. Since East played the HK, it appears that West has the HQ. Hence if Declarer wins trick 1, West will have a heart entry. However, this can be removed immediately by leading a second heart.

Either (a) ducking trick 1, or (b) winning the HA and leading another heart would seem to be good strategies (although neither is certain), but definitely not (c) winning trick 1 and leading trumps. As the cards lay, either (a) or (b) would be successful, and (c) was 1 down.