• The Planning Stage Of Building A Tiny House offers a great way to start the design process: list everything you do in your house, then mark out the area you have in mind for your tiny home, and act out the various tasks, making the movements and imagining the furnishings.
• No. 1 - Tiny House Plan (Free PDF plan download) - Photos, renderings, plans, and detailed building notes for an 8'x20' house on wheels that the designers lived in for several years. Definitely worth downloading.

Some sources for tiny house plans:

• Tiny House Plans compares and reviews several sources.
• Houseplans: Tiny House Plans
• Tiny House Design: Tiny House Plans
• Tumbleweed Tiny House Building Plans

DIY design for beginners:

• TinyHouseTalk: Tiny House Design - A collection of practical, how-to blog posts; includes sketching and modeling from scratch, and design specifics like natural and artificial light, cold climates, passive solar, storage, creating openness, and more.