Apps are big business, with Apple recently passing the landmark of 1.5bn apps downloaded by users, and there are now more than 65,000 iPhone apps in the App Store.

With so many competing apps, developers and brands need to deliver the best possible user experience. Here are a few best practice tips for improving the usability of iPhone apps…

Get the price right

To some extent, the price you set for your app depends on what you want to achieve with the app. For a publisher such as the Telegraph, the iPhone app has to be free, as the aim is to drive reader numbers and ad revenues.

Likewise, if you are seeking to sell through the app, or promote your brand with games for users, such as the Hello Baby iPhone app, or Ocado’s shopping app, then it should be free to download.

For other types of apps, such as the recently released Tube Exits app, then this needs some careful consideration. According to AdMob, half of free apps aren’t really making any money at all, so unless you know the app will be popular, then you cannot rely on ad revenues for income.

In the case of the Tube Exits app, developer Lance Stewart decided on a price (£1.79) that was cheap enough to appeal to users and provide value yet still high enough to cover costs.

Make the most of phone’s functions

Simply transferring an existing mobile site into an iPhone app isn’t good enough, developers need to make the most of the iPhone’s features; GPS, mapping, camera etc.

For example, the Barnes and Noble app has some excellent features that use the capabilities of the phone. Shoppers can take photos of books and video on the iPhone camera and the app will return shopping results and reviews.

Also, the app uses Google maps to allow customers to reserve and collect at their nearest store.

Only send users to mobile-optimised web pages

This is something that several m-commerce apps and websites fail on. They often provide some excellent product browsing options, but when you actually want to make a purchase, you can be sent to the standard website checkout, which can be hard to negotiate on a small mobile screen.

The better shopping apps have desigined checkout processes forthe purpose. The Barnes and Noble sends you to its mobile site’s checkout, which is fine, while  Net-a-Porter has the checkout built in to the app, which is much easier.

Design for slow internet connections

Developers need to take into account the fact that many people will be using the app when they are out and about, and that connection speeds may vary.

For example, while the Independent app is fine is you plan ahead and download stories on a wi-fi connection, if you just want to access the app on the bus and read a couple of articles, the loading time is too slow.

Avoiding the need for loading too many pages, and keeping images and graphics to a minimum will improve load times and avoid user frustration.

Make navigation clear

The iPhone app format, wiht the navigational buttons at the bottom, provides developers with a useful way to navigate around the app much easier than they could on a normal mobile site.

Simple things like linking the logo back to the main menu, providing breadcrumb trails for users to retrace steps, or providing futher reading links from article pages all helps.

Barnes and Noble again provides a good example here, with navigational links along the bottom to the homepage, search function, store finder and shopping cart, while providing breadcrumb trails throughout.

Careful with ads

With many apps relying on ad revenues for income, especially free versions, users will be OK with a certain level of advertising.

The banner ads provided on may apps by AdMob and other are fine, but intrusive ad formats, such as the interstitials trialled by the NYT,  are unlikely to be tolerated by users for too long.

Listen to feedback and update when necessary

While the app should be tested well before release, there may be errors or possible improvements that are highlighted by users. Listening to this feedback and keeping an eye on App Store reviews will tell you about any problems.

If users encounter problems using the app, they will quickly abandon it, so send updates  via the App Store to deal with any issues.