Thanks. I'd be grateful for a brief explanation (example). I can understand how I might believe a stock is going to rise to x in y days but how do I match that / compare that with the implied volatility?
You should read up on some options math and how implied volatility is calculated.
For maturity, its really easy. Do you think the stock will rally above the strike+premium. If not, then sell the put. If so, then buy the call.
For before maturity, you need to understand the cost of time value bleed (theta) against the delta and the gamma. (the theta, gamma, and delta being determined by the implied vol).

