Chaos, the best thing to do is for electric "Supply" charges, is to check your present bill for how much you're getting charged P/KwH, then compare it to how much other companies are charging. Keep in mind, some companies are charging a reduced price as a promotion and the price will go up after the promotion period ends. The other charges you see on your bill will probably remain the same whatever company you choose. So the key words for electric is "Supply Charges" and "P/KwH".
For Natural Gas, check how much is the "Delivery Charge P/Therm".
Hope this helps.