4) Have a realistic price.
Yes, many apps are as cheap as chips. But there are many which are completely overpriced. That is the main reason people pirate surely? Because they can't afford to buy the app. Cutting the price may encourage more people to buy.
I don't think people really "need" the apps they pirate, if they can't afford them (which I find strange considering the average price is well below 5€) they could either not use it or find a free/cheaper alternative.
IMO, if certain app is not realistically priced, then don't buy it. I've yet to find any expensive app that is an absolute must have, so either buy it or skip it.
So far I've bought every app I've felt like installing and that hasn't set me back more than 20€. I'm sure some people might not be able to afford spending 20€ over a couple of years on apps for their 100€+ phone, but I don't think they are a majority.
I'd guess most pirates are either a)cheap, b)scared of using their credit card number on online transactions, or c)kids without a CC whose parents are unwilling to spend money on cellphone games.