What industry do you think your business is most related to?
Before you all start just a hint: Please checkout the photo editing app Snapseed or the mobile wallet app Spendee. We are working on a very cool app for designers to create mockups, therefore the design of the app needs to be great as well.
The name of the app will be "InstaMockup". InstaMockup is an app that allows it's users to create real-world Mockups from their apps/websites (compare to placeit.net). It allows you to plate a screenshot of your app or site in a real world photo. Startups and press are using these images for marketing on their site. Users can then download the images. Please checkout the wireframes and examples.
We added a sample wireframe that explains the app. We also have a first prototype working. The screenshot of the prototype is added as well (orange).
What do you have in mind for the style and theme of the app?
We want to have a modern style and design that matches iOS 7. We prefer a flat design. No need for a custom typo but if you use one please let us know where to purchase it.
It's important to support Retina, so make sure that everything is optimized for 2048-by-1536.
Don't forget that the App needs an Icon as well.
As a tool you can use either Photoshop or Sketch.
Designs that we like are for example the Spendee App: http://www.spendeeapp.com/
YOu first select the background image that you want to use. We provide between 40-50 different backgrounds, some with an iPad, a Macbook, an iPhone or another device. The selected background appears and you have to select the screen that you want to place. Therefore you click a button "select screenshot" and the photo library opens. You select the image and the screen is placed in the background. Now you can share or download the image. Beside this you can open a menu with links to help, about us and terms. The App will have a loading screen at the first launch and it needs an icon, of course.
What to avoid
Don't take the Wireframes and sample screens as design input, it's not. They just show you functionality, feel free in your UX/UI skills to create the best app.