If your company is thinking about building its own app, there’s one rule that should drive all  your decisions: “form ever follows function.”

This principle, originally used in modern architecture, also applies to software, especially in the increasingly specialized market of mobile apps.

The most important thing you can do, before a single line of code is written, is to determine who your target users are and what they’ll use your app to accomplish. Everything starts with this initial diagnosis.

Not All Shopping Carts Are Created Equal

For example, an app that allows a restaurant’s customers to place delivery orders should look and function differently than an office supply company’s online shopping cart.

On the surface, they both offer the same basic functionality—customers use them to buy things. The restaurant’s application, though, should be visually driven so customers can take a look at the food before they order. The office supply store will probably be more data driven and complex because it will be selling computers, copiers and other sophisticated products. Its customers will want detailed information about the equipment’s specs.

Although technically they are engaging in the same exercise, the user looking for an order of mu shu pork is quite different from the user looking for printers. The user interface they expect is similarly different.

Finding the Customer’s Comfort Level

Another important point to consider is the type of software your target user is comfortable using. Someone from the enterprise software world might be more accustomed to the more traditional interfaces of productivity applications like Excel, but a creative type might feel more comfortable with something less traditional and more aesthetically driven like Instagram.

It can be tempting to build something structurally complicated and graphically complex, but that may not always be the best solution, and the engineering and design costs for your application can quickly balloon as the software becomes more complex. Sometimes a simpler application can get the job done just as well, if not better, as the engineers at Twitter and Snapchat can attest.

Mobile or Web?

When deciding how complex a piece of software your business needs, another decision you have to make is whether you’re building a mobile app, a Web app or both. Again, this comes down to knowing what your target users are looking for and what they’re comfortable using.

But, food for thought: According to the Pew Research Center, 58 percent of Americans now have a smartphone, and that number will only continue to grow as technology matures and prices drop. So, if you do decide to go Web-only, be sure to consider mobile users in your design as well.

Create Value

Lastly, make sure the software you’re offering is in some way unique in the value it brings to potential users. Whether it’s a different take on a common feature, a brand new feature or an interesting design, you need to find a way to differentiate your application from the rest of the pack in a way that’s meaningful.

One tried-and-true method is finding a friction point in your customers’ experience and developing a feature that removes whatever makes the experience painful or annoying. Take, for example, cashing a check at a bank, a process that can be fairly tedious and time-consuming when done in person. Most modern banking applications now allow users to cash checks with a photo taken from the banking application. This is a great example of leveraging technology to make a task more efficient and painless while providing real value to a user.

Another avenue for investigation is your business’s internal inefficiencies and how they might affect customers. A good example of software in this vein is the checkout systems used in Apple’s retail stores, which allow employees to track and interact with customers digitally and ultimately to process a transaction in the store digitally, removing the frictions of the traditional brick-and-mortar customer interaction. Because of this software, Apple can offer a unique customer experience that provides value beyond the products they offer in the store.

Whichever route you take, just remember to make it useful and make it unique. Then you can worry about making it work.