The Fret hand fingers should be able to move indepentently from each other in order to change chords of switch strings smoothly. Often, fingers tend to pull at one another creating situations that require planting one finger in order to place the rest. These exercises are a good step in learning the mechanics of your finger movements.
The basis of these exercises come from John Duarte's "The Guitarist's Hands", I've simplified it a bit to make it easier to go through. (I haven't seen the book in about 10 years, so it may or may not be similar).
Take each of the exercises slow at first, to be aware of your hand's limitations. Certain fingers may not want to move alone at first (or even at all) since everybodys physiology is different.
As with any physical movements, make sure that your fingers are warmed up. DO NOT CONTINUE if there is discomfort or pain.
Let's begin. First place your 1st finger at the fifth fret of the third string, then 2nd, 3rd, and 4th fingers at at sixth, seventh, and eighth fret accordingly. We will call this the Home position. We will start with the 4th finger. Keeping all other fingers down, lift the fourth finger and put it on the eighth fret/fourth string (Ex 1) .
Return it to the Home position, then to the eighth fret/second string Ex 2. Repeat this several times.