Start seeking for squares which orientation can be easily determined.
Once you are sure of the orientation of a square you can mark it using themouse button. This is particularly usefull in harder games.
Look for I-shaped and T-shaped wires near the borders, and L-shaped wires near the edges. The position of these squares can be easily determined, unless you are playing the Very hard difficulty level.
When playing the Very hard difficulty level a good place to start looking is near empty squares, if present, and near regions containing many terminals grouped together.
Even when playing with the same difficulty level some games are easier than others, restart the game if you want to get a different board.
If you want to get a good score, only do a move when you are sure.