Copyright Nanette Blanchard, 2008, http://knittingpatternfree.blogspot.com/ Not for reprint on other blogs!
As far as your charted designs, you are best starting with simple geometric shapes rather than trying to chart out complex pictures of woodpeckers or houses or airplanes. You certainly can do woodpeckers but you'll have to remember the ramifications of using long floats (let's say anything over 6-7 stitches of one color). If you look at traditional Norwegian knitted designs you'll notice that in between all those huge snowflakes or stars are a lot of smaller motifs to help avoid really long floats where you're using just one color.
Once you have made your first chart it is time to figure out how to add it to a pattern. Hats are a good choice for a first stranded design project because they usually require less shaping than other knitted accessories and they're usually knit in the round. You can use any plain hat pattern you have and just add in your stranded pattern. However remember that stranded color knitting is a finer gauge than solid color knitting so if you take a plain hat pattern that fits you perfectly and add stranded colorwork all over it your beautiful new hat will most likely be too small.
Gauge swatches are very helpful in this situation. Since you'll likely be knitting colorwork in the round, you should also do your gauge swatch in the round. A simple method of doing this is to use dpns. Knit one or two repeats of your pattern on one dpn then slide the stitches to the right hand side of the dpn. (This action is just like what you do to knit I-Cord.) Take your yarns and pull the strands of yarn to stretch from one side of the dpn to the other and start knitting again. To measure you swatch simply cut the long strands of yarn in the back and flatten in out. That is why most stranded swatches look like they're fringed.
If you're going to do a project with many different stranded designs, make sure you swatch them all. Different stranded charts have different gauges - if you've ever knit something with vertical stripes you'll notice the fabric draws in pretty severely so if you pair vertical stripes with a simple checkerboard design you're going to have a finished project that is different widths on each design.
This first photo shows a chullo I designed with many different stranded patterns. Because every stranded pattern has a different number of chart repeats, it can be annoying to try to fit them all in one design. Because this chullo had decreases all through the hat (done on the plain stockinette rows), I had more leeway in making chart repeats work with the different number of stitches for each row.
You don't actually have to make all your chart repeats match up perfectly at the end of the row. I've seen a few designs where the repeats did not match at the end of the row including the Travelling Socks by Lucy Neatby in the Socks, Socks, Socks book. It is quite a freeing experience to not worry about stitch repeats.
I prefer to try to make everything match up and this is one reason why simpler geometric motifs work better than more complicated ones. It is a lot easier to make a 6 stitch chart repeat fit into a design than a 47 stitch one.
Once you start putting stranded chart designs into your project you'll start collecting what I call "magic numbers." These are numbers divisible by many other numbers so that more color charts will fit into them. I often use 48, 60, 72, and 120 as cast on numbers for projects for this reason.
Make your first project one without gussets. Trying to design gusset increases or decreases (either in the heel of a sock or a thumb gusset in a mitten or glove) while simultaneously doing colorwork can be a pain. Another thing you can do is combine stranded color patterns with solid color knitting for the gussets; for instance you'd do a stranded cuff on a sock then do the rest of the sock (and gusset) a solid color. Just remember that stranded knitting is always a different gauge than solid color knitting with the same yarn and needles so you'll likely need to do some decreasing of stitches as you go from stranded knitting to solid color knitting.
If you do a project that involves increasing or decreasing while simultaneously doing colorwork, figure out in advance what color you want the increased or decreased stitches to be. Most colorwork mitten tops or hats use the same color for the top decreases - I generally go with the darker color for all the decreased stitches but that is a personal choice. I think I've only once done a mitten project that used alternating colors for some decorative top decreases.
There are a few sources out there with info for designing colorwork projects. My blue tam seen below was designed using an excellent article by Alice Starmore. "Designing a Wheel-Pattern Fair Isle Tammy" was initially printed in Threads magazine in December 1988 but is also reprinted in the Threads Knitting Around the World book. The book is out of print but I think it is still easy to locate for a decent price.
If you enjoy doing knitted items for children, the book Style Your Own Kid's Knits by Kate Buller includes detailed information on how to add colorwork to children's sweaters and accessories. Finally, Adrian at Hello Yarn offers a free generic Norwegian mitten and generic Norwegian hat chart grid. Simply add your own pattern to the chart and knit it up.
If you're on Ravelry the Stranded forum is an excellent resource. The forum group pages is the single best Internet reference for knitters who enjoy stranded color knitting. The 17 group pages are full of links to practically every single video and photograph and tutorial of every possible stranded color knitting technique. Check it out!