Good place to start!.
In most cases depending on if the tv is Lcd it`s down to bad capacitors on the main power board that need to be replaced.
If a plasma based set it`s a bit harder.
A quick visual inspection of capacitors, if they are bulged at the top or bottom of them, domed and not flat tell you they need to be replaced.
As well as any sign of liquid that may of leaked from the capacitor its self.
Simply changing the capacitor for a like for like one with the same farad rating read from the capacitor it`s self and the voltage rating of it can often fix the problem of a LCD screen, and tv so it works again, and the screen image can be seen.
Depending on how many capacitors need to be changed and replaced by new ones will determine the cost of fixing it if you do it your self.
Just take note when you remove a capacitor of what side the stripe on it is pointing to of the two legs.
You must fit a new capacitor in the same direction as the stripe is pointing to the leg of the capacitor.
If you place it in the wrong way around it will explode due to passing a current through it backwards.
Stripe on a capacitor is always to the negative side of the capacitor in the circuit.
If doing yourself desolder each old capacitor one at a time, and then place the new one in the right way around.
Then do each one by one.
You can buy capacitors from tandy, radio shack, or if in the uk by RS components.