To make a small slam (bid of 6) -- you need 33 pts.
Extra trumps -- you need at least an 8-card fit to bid a suit slam, but stronger fits produce more tricks. You may score an extra trick for each trump you have over 8.
Long, strong side suits -- if you can set up and run a long side suit, the small cards can be as valuable as honors.
A first-round control (Ace or Void) in at least three of the four suits.
Depending on the situation, you can use Blackwood (to ask for aces after a suit bid), Gerber (to ask for aces after a notrump bid), or Cuebids (to find aces when Blackwood can't be used).
5C = None or all four aces
5D = One ace
5H = Two aces
If only one ace is missing -- you can bid six of your suit or 6NT.
If your side holds all four aces -- and if you think you may have the power to take all the tricks -- you can try for a grand slam by bidding 5NT to ask for kings. Your 5NT bid guarantees that your side holds all four aces and asks partner how many kings he holds. Partner will respond at the 6-level (using the same steps as above) to show the number of kings he holds -- 6C to show none or four kings, 6D to show one, etc.).
A bid of 4C directly over partner's notrump bid is Gerber and asks for aces. Partner's response tells you how many aces he holds:
Remember that Blackwood and Gerber tell you only the number of aces partner holds. They don't tell you which suits they're in or whether you're off a cashing Ace-King in a suit. You should use Blackwood or Gerber only when:
You've already found a good a trump suit (or agreed on notrump).
You know you have the overall strength for a slam.
Once you and partner have agreed on a trump suit, a new-suit bid by you shows a suit where you hold an ace. It asks partner to cooperate by bidding a suit where he holds an ace. To save bidding room when you're cuebidding, both partners should always bid the cheapest suit in which they have a control (an ace or a void). You can also continue the cuebidding sequence to find a second-round control (the king or a singleton). Here's an example:
You open 1S and partner bids 3S (a limit raise with 4 trumps). You want to play in 6S if partner has control of diamonds, but you can't get this information with Blackwood (if you bid 4NT and partner answers one ace, you won't know whether it's in hearts or diamonds). To locate the diamond ace, you must start a cuebidding sequence with 4C to show your club ace and ask partner to cuebid his cheapest ace (if he has no aces, he'll retreat to 4S).
If partner cuebids 4D, you'll know he has the diamond ace and you can bid 6S. If he instead cuebids 4H, it tells you he has the heart ace but not the diamond ace (since he will cuebid his cheapest ace).
Over partner's 4H cuebid, you can sign off in 4S if you are no longer interested in a slam, but this hand is strong enough to continue the investigation. A 5C cuebid by you shows a second-round control of clubs (king or a singleton) and asks partner to tell you more. Since partner's 4H cuebid already denied the diamond ace, he can now cuebid 5D to show you a second-round control. If he bids 5D, you'll bid 6S. If he bids 5H (showing second-round control of hearts but not diamonds), you'll sign off in 5S. If he bids 5S (showing neither control), you'll pass.