I believe ASO is worth investing a little time in, because honestly, it has got to be better than just randomly picking your keywords without doing any research. First of all, I'd advise against paying anyone to do it for you, as it's something you can easily do yourself.
Over the past few months I've been doing a lot of research into ASO with the aim of improving Clear’s position in search results, but before we get into that, here's Wikipedia's definition for ASO:
App store optimization (ASO) is the process of improving the visibility of a mobile app (such as an iPhone, iPad, Android, or Windows Phone app) in an app store (such as iTunes or Google Play for Android). App store optimization is closely related to search engine optimization. Specifically, app store optimization includes the process of ranking highly in an app store's search results and top charts rankings. — Wikipedia
I think that sums it up fairly well. Let’s get started by taking a look at how search works in the App Store and why it matters.
Why search matters
Apple regularly makes changes to try and improve the search algorithm on the App Store. Similarly to Google, no one knows exactly how the App Store search algorithm works, or exactly what Apple takes into account when a search is made. The fact that you can only change the app name and keywords at the time of submitting a new binary makes it very difficult and time consuming to find out what works and what doesn't. I'm 100% sure this is the way Apple likes it.
From experience, speaking with other developers and studying the top charts, it would appear (unsurprisingly) that the following things matter; App Name, Keywords, Ratings, and most importantly the number of Downloads.
An app’s name, and the keywords it uses are some of the biggest influencers in search results; all the research I've done suggests that the download volume acts as a multiplier on the name and keyword match. For example, If two apps have the same keyword (and rating), the app with the most downloads will come out on top — I've experienced this first hand with Clear for iPhone & Clear+ for iOS.
In August Apple made some big changes to the search algorithm on the App Store, I read the article at the time and thought nothing of it. However, over the coming weeks the revenue for Clear suddenly went down. There's no way of knowing if this is because of the changes Apple made to the App Store or because of some other external force, but here's a graph showing Clear's revenue from June to November:
As you can see, towards the end of August revenue falls significantly. Ouch!
Can ASO help?
The key to getting good results from ASO is to monitor and tweak the keywords every time you update your app. To do this for Clear I signed-up for MobileDevHQ (they have a free indie plan), it's pretty good and helped with tracking the popularity of the keywords I was interested in. After looking at the results and monitoring this for a while I decided we should push out an update to Clear and Clear+ and change the app name along with some of the keywords.
For the iPhone only version I changed the title from Clear to Clear - Tasks & To-Do List, and the iOS version from Clear+ to Clear+ Tasks & To-Do List. I also corrected some common keyword mistakes. These errors included using the app name, repeating the pluralised versions of other keywords, and being under the 100 character limit. As expected, I didn't see a huge change in our download rate, but one of the most remarkable changes I did notice was the position of Clear+ when searching for "to-do".
From November 14th to the 26th Clear+ had hovered around #250 when searching for "to-do.” On November 27th (the day after we released the update) it shot up 100 places to around #140 on the search term, and since then it's continued to rise. The iPhone only version of Clear has been in the top 10 for this keyword search result since August so there was no noticeable change there.
I think the biggest change for Clear+ was due to the fact that we put the search term "to-do" in the app title. The original version of Clear always ranks higher than Clear+ because of the download volume and number of ratings it has amassed since it's launch in early 2012.
The number of downloads seem to be one of the most important factors in helping apps get found, but unfortunately this is one of the harder things to improve upon. There are methods to help with this, though - If you have a paid app, you could consider a sale or going free for a few days to try and gain more downloads. If you do decide to put your app on sale be sure to let the press know in advance to help give your app some extra exposure. Even being mentioned on one or two sites can make all the difference.
App title snobbery
Before I started looking more closely at ASO I'd always been a purist about naming apps; I used to mock others for adding keywords to the end of their app titles. However, it's now apparent that our own apps were losing out to lesser apps because we weren't doing the same. It's not very pretty and I don't like doing it but unfortunately it seems you need to play the ASO game or you're going to get left behind. If you're going to add keywords to your title just try and stay classy.
Let's be honest, ASO is not going to make a huge difference to the number of downloads your app gets and it certainly won't make it a success overnight, but if done right, it can make a difference.