I do not want to focus on the tools, as there are many tools out there which can help you build a landing page easily: http://unbounce.com, http://kickofflabs.com, http://launchrock.co and http://launcheffectapp.com will do the job just fine. This is the easy part.
Instead, I would like to focus on something else: your content.
When creating a mobile app, you need to have a target group in mind. In your case, this target group is musicians. Your landing page should ultimately bring you subscribers that will convert to customers. I mean, there is no point getting the email address of 10,000 people if only 20 of them are truly interested in your product. You'd better get 1,000 addresses of people who really want your service.
How do you achieve this?
There are three crucial elements your landing page should include:
1) A short description of the app
2) A high quality image or video
3) An email field + a "subscribe" button
The description should explain what need your project covers, in an understandable and short way. Preferably, it should be approximately 160 letters, so as to be easily "tweetable". This is exactly what Steve Jobs did with the description of EVERY product he launched. This way, the audience could easily tweet what he said. Your visitors should be able to grasp the core concept of your service within a couple of seconds.
The image / video could include high-quality graphics or simply some screens of your application. It should enhance the description and give a "wow" factor as much as possible.
The email field should make a contrast to the rest of the visual elements of the page. Your visitors will be able to see it immediately. The subscription button should be visually highlighted and its text should relate to the action. Avoid using words such as "subscribe", "OK" or "Go". Instead, use something more meaningful, like "Notify me".
Personally, I like to include the following information as well:
- A list of 1-2 problems the application is addressing.
- A list of 1-2 main features / solutions to the above problems.
- Additional images or screens, if the design of the app is ready.
- Social media links (Facebook, Twitter, Google+, LinkedIn, Pinterest).
- A press kit for journalists. Journalists covering the entrepreneurial news are constantly seeking for information about new projects. I do the job for them and provide a zip file with documents and images about the upcoming products.
If the page turns out to be quite long, I include an additional subscription field in the end of the page. Remember: your are trying to make people trust you and provide you with their email address.
How long should you keep the launch page alive? Well, this depends on what you are trying to build and how much time the development team needs to work. For small apps, a month or two would be fine, but most products take way longer. The time period does not really matter if you use your email list wisely.
There is no "too quick" or "too slow". Read on to learn why...
From my experience, people tend to forget. You need to remind them of your product periodically. Sending an email once a week would keep your subscribers engaged and will maintain a high desire for your product. Additionally, you could start a blog and post once or twice a week about the problems of your target audience and the upcoming app. Your posts should include a link to the app launch page. Share your knowledge about the pains of your audience and promise a solution. Starting a blog is easy and free, too.
Now, a few words about marketing and advertisements... Think twice before spending your whole budget on Facebook and AdWords. Although they can both work, in such early phases of a project, you need to focus.
Here is an action plan I suggest:
1) Build your launch page.
2) Create a blog, along with social media profiles.
3) Search Facebook, Twitter, Google+, LinkedIn and Pinterest about groups and pages that your target audience likes and/or is member.
4) Publish a blog post once, twice or more per week.
5) Share your posts and your launch page on every of the above groups and pages.
6) Keep your audience engaged with regular updates and emails (do not email them more than once per week though). When you send them an email, always ask for feedback. This way, you generate trust.
7) Follow the leaders of the industry you are targeting and find the journalists who cover the relative fields. There are online tools that connect you with journalists. Talk to them in person and try to find out what they think about your product. Let them promote it via their media.
8) (Optional) Review and modify your landing page description and text according to the feedback you receive.
If you want to spend money on online advertisement, consider using the audience targeting tools by Facebook and Google. Specify you target group as strictly as possible.
One more thing: do not underestimate any social platform. Facebook is not the only solution. Each target group might use a different social website most. Here are two examples from my own experience:
1) I had developed a landing page for a Motion Application that targeted Software Engineers. 50% of the traffic was coming from LinkedIn and only 20% from Facebook.
2) Another landing page of mine was promoting a travel app. I had paid many thousand dollars on Facebook Ads and AdWords. However, the majority of my visitors was coming from Pinterest with no ads.