The secret is to ask yourself: what can you offer that your clients need? Why should they work with you? Once you know you need to work out how to get their attention?
heidi_helen - "Have you ever suffered from imposter syndrome, or struggled with feeling good enough about your work or for your price, and if so have you managed to overcome it?"
thadcoxdesign - Of course, everyone does. But it's usually because you're too close to your work and have lost perspective on your talent. By helping others, not only does it feel great, but you soon realise that you know more than you thought and this builds confidence and conviction in your own work.
Start sharing your knowledge, teaching what you know and always over-deliver for your clients. The responses from appreciate designers and thrilled clients will banish any feelings of imposter syndrome.
Also, look back at old work, you'll be shocked at how bad it is!! That's when you'll really see how far you've progressed.