Unless your DM replies "always" do not play the Wild Mage.
No other class is competitive at below maximum performance, there's no reason to believe the Wild Mage is different.
Ath-Ketins suggestion and others only mean one thing: avoid. They might sound reasonable, but really aren't.
Unless the player gets to be in full unrestricted control over Tides of Chaos and can use it freely at will (up to each and every time he casts a non-cantrip spell), do not play the Wild Mage.
Some people don't play for optimization. Some play for flavor.
That is true.Some people don't play for optimization. Some play for flavor.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.