Learn to Knit - Weave in Ends
The first step of finishing is weaving in the yarn ends. Securely woven ends will not unravel during washing and pop out on the front of your project. You will always have at least two ends to weave in—the excess yarn at the beginning cast on edge and the excess yarn after the bind off. If your project uses many colors or combines different types of yarn, you will have more ends to weave in.
To securely weave in an end, thread the end through the eye of a blunt yarn needle and work from the wrong side of the piece. Weave the needle through a few of the stitches, turning the piece over to be sure the needle isn't visible from the front. Pull the needle to pull the excess yarn through the stitches. Repeat this for an inch or so, and then turn and weave in the opposite direction. Trim the end close to the work. Some people prefer to weave diagonally, some horizontally or vertically—do whatever makes the most sense for the project, making sure the yarn does not peek through the front of the piece.
Bulky yarn will need to be woven more than an inch to prevent the end from unraveling.
If you have many ends to weave in, do not leave them until the end of the project. As you finish a garment piece or a few inches of a stripe pattern, weave in the ends as you go.