So what have I learned after eight months on the App Store?

Around 11 months ago I registered my App Store developer account. The idea...put Vizati on the iPhone.

I've never worked with Mac's before, didn't even have an iPhone/iPod or whatever. I just read that a bunch of people got rich and many more where making a living out of it.
So here I go.

Just placing an app there will sell

My first BIG mistake was the general conception that "just placing an app there will sell". That's probably true on the very first months the App Store opened. Not now, trust me. You release a new game, will probably have a few sales on the 1st day because it's on the new released games and that's it, only on very rare conditions will the game start selling very good with just that.

So keep in mind advertisement on iOS is mandatory, forums, twitter, mailing list, whatever.
The first month I was sending dozens of emails every single day to websites, journalists, magazines, some paid off, others didn't.

Release my app at a Thursday to be featured at that week's App Featured Apps

Although this might increase your odds, we released Vizati on a Friday, 2 weeks later it got a feature on the App Store, so it can still happen. Just create something cool and appealing.

$0.99 is the way to go

Wrong, don't EVER place your app at $0.99 right from start. Evaluate it well, start higher. Having a higher price will help to distinguish it from others, will give you margin for promotions without making it free.

Many costumers, tired of the enormous lists of game will only seek higher priced games because logic mandates that they are indeed better. If you think your app is not worth more that $0.99 go back to the drawing boards. There's no sense in having crappy apps, 100 bad apps may not sell as much as 5 really good ones.

Selling at a low price will also bring all kinds of customers, they will give you a 1 star just because you haven't updated the app in 5 months or so. Customers that buy pricier app are more forgiving and respectful.

Making a Free promotion will help boost sales afterwords

True, for the first 2-3 days. Then you'll get back to whatever you where selling. Unless you have some in-game purchases it's not worth it. Well only if you want to brag to your friends that your app got 100K downloads no matter the price.

I've tried this 3 times, each time I place it at a smarter occasion getting successfully more downloads, thing is that after 3 days of getting back to regular price things would slowly return to normal.

Depending on promotion amount of days you may end up with the same money you would have not making the promotion. Also usually you will see your rating decreasing half or a full star, keep in mind, all kinds of people will download it.

Answering to customers Feedback helps sales

Obviously implementing a highly demanded features will make them happy thus recommending to friends. Just don't go making all the changes they ask. Choose a position and defend it, show that things are the way they are because you choose so, not because of some mistake.

People will buy all kinds of crap, just place one level.

Also true, but just because they bought a "fart app" doesn't mean they wont' complain about your 15m duration game.