Below you will find a number of tools and methods which can be used to boost the creativity and efficiency of a product development cycle. Of course these are only brief descriptions of the tools, and there are many other methods out there.
The Double Diamond
Divergence and convergence, exploration and distillation, expand and contract; these terms refer to what is typically now called the "Double Diamond" design process. Promoted by the British Design Council, the Double Diamond is the representation of a process that was found to be utilized by many prolific and successful designers. The two diamonds are divided into four stages, known as Discover, Define, Develop, and Deliver. The first diamond (Discover and Define) addresses the design problem, and the second (Develop and Deliver) is focused on the solution to the design problem.
Recognizing a potential design problem is one thing, but understanding it is the real goal. In the Discover phase, the problem is explored in order to see how it interconnects with the user and the environment. This phase may uncover a number of other design problems that contribute to the initial observation.
In the Define phase, the information gathered from the Discover phase is distilled into a singular, driving, design question. The capabilities of the designers or the company, the state of current technology, and potential market sizes can all contribute to crafting this problem definition.
Like the Discover phase the Develop phase is a period of broadening possibilities, but now the focus is potential solutions to the defined problem. The explored concepts can range from system level to the tiniest component, and permutations therein.
In the Deliver phase, the potential solutions are vetted and polished based on input from market predictions, engineering and manufacturing concerns, and user feedback. By the end of the process, the resulting product should be a strong contender for meeting or exceeding the goals of the users and the producers.
Brainstorming is a staple of initial design effort; many studies have looked into methods for making the most of individual and team brainstorming sessions. A common practice for more effective brainstorming: refrain from judging ideas and thoughts during the session.
Life has had millions of years to adapt to the many tasks and trials it faces, and translating these adaptations into design solutions can have great results. After taking a walk in the woods, George de Mestral was inspired by the burrs clinging to his pants to create Velcro hook and loop fasteners.
A persona is a fictitious user created by designers to aid them in understanding their target customers. Market research and the basic principles of the design task initially determine this persona. By exploring the habits, goals, and social interactions of the persona, design choices can be made which will make the end product more attractive to customers represented by the persona.
Laddering is a thought experiment use to understand the deeper factors contributing to a design problem or a user need. Sometimes described as "the five why's" it can mimic a young child asking "why?" after each answer they are given. For example, a person does not want a wristwatch simply to possess it, but instead wants it in order to be more punctual, or present some sort of social status, or display personality traits they have or wish to have. By understanding these deeper drives, choices can be made for the design of the product so that it is more effective or desirable.
Understanding the available products in a market can uncover potential market gaps, where a desire for a feature or combination of attributes is going unanswered.
Design Structure Matrix (DSM)
Design structure matrices can be used to quantify the flow of a product development effort. This can be helpful by predicting iteration cycles and mitigating the effect they have on other tasks in the process.
Quality Function Deployment (QFD)
QFD is a tool used to translate qualitative aspects of user needs and desires into quantitative measures which can be used as engineering and system specifications.
In a system where aspects of the design compete with each other and the solution is not obvious, optimization techniques can find a balance based on driving criteria. While this can be powerful, it requires an accurate model of the system behavior.
The Kano Model deals with product features as they appeal to customers. One important phenomenon highlighted by the model is how delightful innovations will, over time, become standard features expected by the customer.
User Research Tools
Surveys are well-known sources of user feedback, but it is important to realize that they are not all created equal. The target audience, question construction, and survey length and ordering must all be carefully considered to reduce sources of bias and generate valuable data.
Bringing your product to users is a very effective way to find issues and unmet needs, but like surveys it must be done in a carefully controlled way in order to get the best results. For this reason, many companies have dedicated user research teams or use outside consultants.
Observing potential users in their real world environment can be a powerful tool for understanding their habits and the problems that they encounter. It is especially important for niche products which will be used in occupations, environments, or social structures that the designer is unfamiliar with.