Bidding is the most important part of the spades game. With a good bid a player can always achieve at least his goal. Bid conservatively - it is better to have one or two bags instead of not getting points on all your bids. Try to never get set. Also bidding NIL is risky and not really worth it statistically. Better to bet one and play it save.

Always look at what the other players have already bid. Never make the total sum of bids higher than 13 if you are last to bid.

There are many Spades Strategies out there that tell you how to count your tricks when you bid. The following technique is very easy and straight forward.

The following table shows how many tricks to count for your non spade cards:

Cards held	Tricks
Ace	1
King and any other card in same suit	1
Queen and two other cards in same suit	1/2
No cards in a suite (subtract on trick from your spades)	1.5
One card in a suite (subtract on trick from your spades)	1

And here how to count the tricks you should make with your spades:

Spades held	Tricks
Ace	1
King and any other spade	1
Queen and two other spades	1
Ace, Queen and another spade	2
King, Jack and two other spades	2
4 spade cards	1
Any spade card when holding more than 4 spades	1/2

With this table at hand you can go off and start bidding like a pro. With a little practice you will not need the table in front of your eyes any more but you can just know by heart how to bid. What if you get an estimated bid of a half a trick? You need to decide if to round up or down. Generally it is better to round down and play conservatively. Many players will take the risk and round up.

Bidding a nil is risky but sometimes it is worth it. If you have many cards in one suit ("a long suit") so it is much better to bid a NIL than when you have many low cards. If you have the cards 2,3,4,7,8,9,J,A in a suit so all there is left in that suit are the cards 5,6,10,D,K. You have enough low cards to go under the higher cards and you can easily not make a trick in this suite.