Whether you're new to industrial design or are a seasoned product designer, we all experience a form of "designer's block" occasionally. There are plenty of processes to help you break through but which one is best for the particular situation you're in? Each technique described below has its advantages to exploring how to sketch in a creative and fluid manner.
Silhouettes allow for a more organic and freeform conceptualization process. If you know what you're aiming for but you don't know where to start, using Silhouette can provide a little bit of a nudge to help you begin nailing down forms in your design quickly and effectively. Think of it as cloud watching but you're in control, adding or removing volume and depth by chiseling away or adding additional values. Silhouettes can also give you a sense of the weight of a design and whether it feels too light or flimsy.
Shapes involve a more predefined conceptualization process, allowing you to see what might fit into your design parameters. If you don't want it to have hard angles for instance, you can avoid those by using softer shapes instead. You're putting more thought into the feel and aesthetics. You're not worried about how it functions. Begin with different simple shapes and build on them. Keep your concepts flowing by using your Lasso Tool to create a new layer via copy, haze it out and build on top of a previous concept so you're not starting from scratch and can progressively integrate your favorite elements as you go.
Lines of Action
If your design feels too lifeless and rigid or unappealing, using Lines of Action can bring energy into your design to show movement and fluidity. A single curved, flowing line that mimics the ear, for example, can provide a foundation that you can build onto with a few shapes that borrow from that line's movement and further inspire your design.
If these methods still don't help you, take a step back and make sure you have all the parameters you need to be successful. These boundaries are what you want to adhere to so you have a clear roadmap to follow when you are conceptualizing the product you are trying to represent. And, ultimately, a bit of fresh air never hurts either.
As a Digital-Tutors member, you can learn how to confidently create concept designs for any product with a proven process on Conceptualizing Products for Industrial Design in Photoshop, one of many Photoshop tutorials, CAD Sketching tutorials and 2D Illustration tutorials in the Digital-Tutors training library.