When you near the end of a ball of yarn, try to change to the new yarn at the row edge. This will prevent uneven stitches in the middle of your work and make weaving in the yarn tails much easier, because you can hide them in the seams.
Step 1: Using an overhand knot (to be removed when finishing the item), tie the old and new yarns together close to the needle, leaving a 4- to 6-inch (10-15cm) tail on both yarns.
Step 2: Drop the old yarn, and begin knitting with the new one. Once you are more experienced and feel more comfortable with controlling the yarns, you may choose to omit knotting the yarns together and simply drop the old yarn and start knitting with the new, tightening and securing the yarn tails later.
Another option is to hold the old and new yarn together and knit with both for a few stitches. Then drop the old yarn and continue with the new. This method attaches the yarn securely and decreases the number of ends to weave in later, but it can leave a noticeable lump, so don't use it in a prominent place.
When changing colors somewhere other than the end of a row, drop the old color on the wrong side, pick up the new color from underneath the old, and continue knitting with the new color (fig. 21). This prevents a hole from appearing between colors.
Sometimes called Fair Isle, Scandinavian, or Norwegian knitting, stranding is a technique that allows you to use two colors of yarn on the same row, carrying the yarn not in use across the back of the work (fig. 19a). Fair Isle knitting traditionally uses no more than two colors per row. Scandinavian stranded knitting often uses more than two colors per row. Choose patterns that avoid overly long strands (anything more than an inch worth of stitches). Otherwise, you'll need to weave in the yarn not in use to prevent snags when wearing the finished product. To weave in, strand the yarn not in use over the working yarn before making the next stitch.
It is possible to knit with the yarn held in one hand, either American-English or Continental style, but you can knit much faster and control the tension (uniformity) of the stitches if you learn to knit with a yarn held in each hand (fig. 19b). Not only can you make beautiful sweaters with this technique, but you can really impress your friends when they see you knitting with both hands!
Knowing how to knit buttonholes is an important technique for sweater patterns. Learn more in the next section.