I feel that most board games favour clearer rulebooks over short sentences, so they'll often tell you the number to deal based on the number of players.
If you prefer a shorter sentence:
Shuffle and deal out all the cards evenly amongst the players. Set aside any leftover cards - all players should have the same amount.
If you wanted to go with something like bwarner's suggestion, but the other way around, then you can get a very unambiguous explanation. By removing the extra cards first, you don't have to pay attention while dealing the rest.
The good thing about doing it this way, is that even though it takes up a little more space in the rulebook and takes a little more time to read, setting up the game might be slightly quicker.
(I'm not sure if the set aside cards can be used later in the game, so I've given you options in italics and grey boxes)
Setup
1) Shuffle the cards.
2) Depending on the number of players, draw a number of cards face down and set them aside return them to the box. They will not be used in this game.
The number of cards to remove is as follows:
Players | 3 | 4 | 5 |
# cards | 2 | 0 | 0 |
3) Deal out all of the remaining cards evenly.