Last week, I began a series of posts on apps for the publishing industry. Why do they cost so much to produce? How do great apps get lost in the App Store slush pile? Are they really a viable new product for the publishing industry (Nicholas Callaway thinks so)?

And I promised to produce a new indie app and pass on what I learn.

Time to dig through the slush pile.

App marketing – FTW

Big corporation spends big money on big brand app and fails. Why the fail?

Corporates have expectations. Budgets can be substantial. Returns need to be bigger. What looks like a win to an indie feels like career death in an institution.

The most common app marketing hurdle lies in understanding the politics of the App Store. The App Store isn’t Waterstone’s. It’s not even Amazon. Accessibility and visibility are both key, but nearly out of reach for most marketing campaigns. Here are a dozen App Store pointers to keep in mind when you’re promoting your next book app:

• It’s all about the charts. If you’re not in the top 10 in your category, you’re nearly invisible. Once you’re in, you’ll stay alive by updating your app, creating new promotions and lowering your price. Then you’ll die

• Your rank is not based on how many apps you sold today or yesterday. The best research I’ve seen suggests the ranking formula is 8x the sales of the current day + 5x the sales on the two proceeding days + 2x the sales on initial release date

• As above, sales rise 20% over the weekend, plus an additional 20% on Sunday. This makes it advantageous to start the weekend in the Top 10

• Conventional wisdom says a Friday release is ideal. I disagree. Based on the previous two points, a Wednesday release is ideal for a weekend peak

• Apple is your friend. The main boost for app sales is to be featured in the App Store. How does that happen? Great design. Something new. Quality. A friend at Apple never hurts

• The App Store is the race to the bottom – don’t fight it. Look at the pricing schedule of Nursery Rhymes with StoryTime. In the two and a half weeks of its life, the app has gone from $4.99 to $0.99. It’s a great strategy to stay in the charts until your update arrives. Just be sure to start high enough to give yourself room to discount, then shout about it when you do

• Unconfirmed rumour: promotion code downloads count toward your rank. When you release an app, Apple gives you 50 promo codes. Make those codes count. You get more with each release of your app, so plan plenty of updates

• In fact, have an updated version of your app ready before your first version hits the store. Every update is a new promotion opportunity

• Unconfirmed rumour: you’re more likely to be featured by Apple if you build a supporting website for your app

• You can update your app description any time. Do it

• Lead your description with a quote – it doesn’t matter who from, as long as it’s nice

• Traditional social media promotion for apps is a luxury, and likely not worth the money. After you’ve harangued your 300 BFFs to press the Like button on your campaign page, you’ll have to start paying one unit of your local Western currency for each new fan. Try Game Center or OpenFeint instead

• Finally, keep it under 20Mb. 3G app downloads are limited to 20Mb. Anything more than that and the customer has to be on wifi – a big deal in the US, where there are far more 3G iPads than in the UK.

There’s more to know, and loads I don’t know. Add your tips in the comments. Meantime, I’ll post elsewhere today on progress with the indie app.