Sit on your hands, is the shorthand advice

When you see a good move - look for a better one, if you can't see a better one then
make the best move you have seen so far.

Many times there is no clearly best move - and you have a choice of many
in that case make the one that a) completes development b) moves (or points) more pieces to where the action is
(or where you think it will be [which can be on attack or defense])
(or you know you need to prepare [for attack or defense] ) - pick a move that does as many of these as possible

black to move !

Farrell-Gray_29_may_2011_A (38K)Black has a very powerful position
but was uncertain how to continue, decide to increase the pressure,

black moves Be3 check

Farrell-Gray_29_may_2011_B (38K)
white's Queen is attacked and it looks very much
as if the White King has to be abandoned - i n fact white has
a small resource (though it ultimately will not save him - in fact
Bxf6 was a stronger move [ but the move that was played wins t00 - just takes a little longer] )

what happened in the game was that white's king found itself forced to go to d3 and black
gave check with a Rook on d8 - becoming completely developed (black's light-squared Bishop was on f3 at the time