Quote from rew:
A fair question, and there's no hard and fast rule. The deeper in the money the higher the delta, the lower the leverage, and the less the time value -- in short, the more the option acts like the underlying asset. High delta is good. If the underlying stock creeps up 0.25 an in the money call with a delta of 0.7 should go up at least 0.15 while some OTM call you bought for 0.30 might not go up at all -- especially if time is ticking by so your negative theta is working against that small delta. Which brings up the other point -- the smaller time value of the ITM call. That's also good, because that's the money you'll lose if you have to wait while the underlying asset goes nowhere. Too many beginners just look at the leverage (the only advantage of the OTM options), largely because of excessive optimism. (High leverage is great *if* the underlying asset moves in the direction you hope and as far as you hope, but experienced traders know that hope isn't a good basis for a trade.)
So the bottom line is, consider different strike prices, and work out how they'll behave as the underlying asset moves by different amounts *and at different times* (taking time value into account). Ask yourself, "What do I lose if I'm wrong?"
Also consider more complex option combinations that can make your net theta less negative or even positive, and lower the overall cost. But in that case make sure you have a broker with cheap option commissions.