Usually you do not bid if you do not have any aces. However, if you
have an otherwise strong hand, with a very long suit (six or more cards
in a suit), you can consider bidding.
You should generally have at least five cards in a suit (with at least
two (preferably at least three) of those face cards or aces) in order to
consider calling trump in that suit.
If you or your partner wins the bid, and you two do not get at least
that many points in the game, then you lose the number of points you
bid.
You can pretend your hand is stronger than it is in order to force
your opponents into bidding higher (this is known as "bidding
up"). This is usually done only if your partner has already passed,
because bidding up your partner is foolish. And if your hand is
particularly weak, be careful that your opponent doesn't give up the bid
before you do!
Remember - trump is not called until after all cards have been
passed!
The person who is calling trump may not look at the cards passed to
him until he calls trump.
Nobody else may look at the cards passed to them until they
themselves have passed cards.
Generally, but not always, you should pass your lowest cards.
Do not pass any point cards if you can avoid it.
If you are calling trump:
Do not drop or pass trump cards. (In EXTREMELY rare cases this
could be unavoidable. I've seen it happen only once.)
Try to void yourself in one or more suits (i.e. get rid of all cards
in these suits). That way, you can probably trump points in the suits you
don't have.
Remember to drop a card!
Since you get to keep the points a dropped card is worth, consider
dropping a five or a ten, since they are usually not that powerful.
You must drop a card, pass three cards, and wait until everyone else
has passed before you can announce what trump will be.
You may not pick up the cards passed to you until you call trump.
If you are not calling trump:
You can often tell what trump will be by what cards aren't in
your hand. Try not to pass trump.
If you are not sure what trump will be, try passing three cards of
different suits. Passing one trump is much better than passing three
trumps.
If you are passing to the person who is calling trump, try passing
into suits you think he will void himself in (i.e. not trump).
Pass to protect your ace. In other words, consider passing a low card
in a suit you have an ace in so that your opponent will not be void in
that suit when you play the ace. Getting an ace trumped is no fun if it's
your ace!
If an opponent is calling trump, consider protecting your partner's
aces, as well, if he has any.
Voiding yourself in a suit is risky, but it works nicely if
that suit is not trump.
You must always follow suit if you have in your hand any cards of the
suit that was led. Otherwise, you may play any card in your hand.
Always play your non-trump aces and kings as early as possible to lessen
the chances that they will be trumped by an opponent that has gone void
in that suit. Of course, don't let a king be taken by an opponent's ace.
When playing with a standard deck, remember that there are 14 trump
cards. (There are 15 trump cards in a Rook deck). Try to keep track of
how many trump cards have been played (especially if you
called trump).
The rook is a trump card! This means that it may only be played if
trump was led, if you are void in the suit that was led, or if you
yourself lead the rook. (Leading the rook is usually a foolish thing to
do, of course, since it is the lowest trump.) Conversely, it must be
played if trump was led and you have no other trump cards.
You should also try to keep track of at least the highest cards left in
the non-trump suits, as well as any points that haven't been played.
If you are third or fourth to go, and it is clear that your partner
will win the trick, give him points if you can. However, if he played an
ace and you have the king of that (non-trump) suit, you might want to keep
the king so that you can win another trick, but that depends on how strong
you think your opponents are, and whether they are likely to go void in
that suit.
If your partner called trump and you have the king of trump, you
might want to play that king early to make things easier on your partner
(that way, he knows that an opponent didn't have the king).
If you called trump, remember that you want to save a card (which
doesn't always have to be trump, although that's often easier) that will
win the last trick.
If you didn't call trump, and the person who did knows what he's
doing, then it's unlikely you will win the last trick. That means that if
an opponent called trump, try to get rid of any points in your hand before
the last trick (preferably, try to win those points - you stand a much better
chance of winning the second-to-last trick than the last trick if an
opponent called trump).