I am currently working on a hat pattern that uses different colors, I do not want to have to sew in lots of tails upon finishing my hat, so I have carried all of the colors along the seam of every round.
In this picture you can see the inside of the hat with the beginning and ending strands of yarn.
On the exterior side of the hat you can barely notice what has been happening on the inside of the hat
This is how I achieved this as I ended and started each and every round. I folded the non working strands over my hook and pulled the new working yarn through the non working yarns and then through the stitch on my hook and made a slip stitch, to join the round and to begin a new round of my hat.
I then pulled the non working strands nice and snug against the beginning of the round I am now working into. Those non working strands of yarn are now ignored as I continue to crochet this round, you do not want to work over them any further as they will not be in place for the next color change.
If you click on the picture below to enlarge it you will see that every strand is neatly tucked away.
This helpful tip is brought to you with pleasure from Cats-Rockin-CrochetGoogle