In my Guide to Blessings, I originally advocated assigning Blessings as follows:
Pattern 1: Combined Might/Wisdom
Paladin 1 - Light on tanks, Wisdom on hunters, Salvation on everyone else
Paladin 2 - Wisdom on casters, Might on melee and hunters
Paladin 3 - Kings
This pattern has its advantages, mainly that all the complexity of blessing assignments is put on the shoulders of Paladin 1. This means that Paladins 2 and 3 have simpler assignments, which can be a great boon for an entry-level raid.
However, this pattern does have disadvantages. To maximize effectiveness, Paladin 1 needs Improved Wisdom, while Paladin 2 needs both Improved Wisdom and Improved Might. Paladin 3 needs Kings, of course. It is rare that you will get 3 paladins with exactly the right buffs, especially if you run a Retribution paladin.
So let's take a look at a second pattern:
Pattern 2: Split Might/Wisdom
Paladin 1: Light on tanks, Salvation on melee, Wisdom on casters and hunters
Paladin 2: Salvation on casters, Might on tanks, melee and hunters
Paladin 3: Kings
This pattern greatly reduces the requirements for maximum effectiveness. Paladin 1 needs Improved Wisdom, Paladin 2 needs Improved Might, and Paladin 3 needs Kings. This is much easier to get, and works well with a Retribution paladin.
The downside is that the complexity is split up between the first two paladins, and no single paladin is responsible for keeping Salvation up.