1. List your packages from highest to lowest in cost. Users will perceive prices to be more affordable.
$999 - $100 - $50
$50 - $100 - $999
2. Communicate just the right amount. List the most important differences (not similarities), but not the kitchen sink.
3. Huge font for prices has shown to convert better.
4. Have a trial period. Giving users a way to test out the app before actually getting charged takes away any risk.
5. In terms of number of packages to have, between 2-4 is ideal. Too many choices will lower your conversion rate, while too few will lose you money (a small percentage of users will always pick the most expensive package available).
Most of all... A/B split test all these suggestions. One size never fits all when it comes to pricing tables.
Depending on the product you're selling, I've found that giving away limited-time discounts converted worse than giving away extended trial periods.