5 pieces of advice for the non-chessplayer

If you ever get asked to do a chess display/simul/challenge against the general public, chances are you will be playing people who may know the rules (although not all of them*) of chess, but not much more. Therefore you will often be asked to give some general advice or tips on how they should play. What I have found is that even simple advice to the aspiring chessplayer (occupy the centre, checks and captures etc) tends to be a little complex and even simpler advice is needed.

1. After you move, your opponent gets to move. What this means is you shouldn't try moves/ideas that only work if you opponent doesn't move at all all. An obvious example is if a black pawn pushes to h2, in an attempt to Queen. White should stop it by playing a rook to the h file, not by playing a rook to the second rank. Sure, if Black didn't move the pawn again then Rxh2 would be good, but given that Black has played h5-h4-h3-h2, h1(Q) is probably on the cards.
2. Pieces that do more are worth more. I've seen novice players decide that capturing 2 pieces/pawns for 1 is always a good trade, even if the sequence goes NxP, PxN, BxP. Rather than getting players to remember 1,3,3,5,9 as the value of pieces, it is often simple to start with "Queens best, Rooks next, Bishops and Knights the same, then pawns last"
3. If you can't think of a move, choose a piece you haven't moved yet. Clearly this is a piece of opening advice, but it also helps players realise that moving the same piece over and over is just a waste of time. You can even upgrade this to "Move the piece doing the least" with little pain.
4. Threaten two pieces at once. This exploits the fact that most non-players are so pleased that they can spot one threat that they don't even look for another. Of course it doesn't normally work against good players but against players of a similar ability it is often enough to start collecting enemy pieces.
5. Threats come from everywhere, and pieces can change direction It is almost like watching traffic. Novice players watch you piece sweep across the board, and then assume the piece will move like that next turn. You can see their eyes trace out the path. And it comes as a big shock when the piece changes direction next move, capturing a stray Queen/Rook etc
   

*I'll always point out checks when a player fails to spot that his/her King is attacked. I'm also happy to explain castling. However if I player leaves an en-passant capture for me, I'll almost always ignore it as this is the one rule guaranteed to cause confusion (if not accusations of cheating!), and it just isn't worth spending 5 minutes explaining it.