Let's say that you casted on a garment and knitted in garter and bound it off. Now, the instructions want you to pick up stitches along the cast on edge and knit in the other direction with the same matching yarn. In this case, you could pick up and knit all in one row and it would probably look great. (Just like when you pick up and knit stitches on the seams of a sweater.)
Now, let's say that you casted on a garment and knitted in garter and bound it off. This time the next instruction is to pick up stitches along the cast on edge and knit in the other direction using a moss stitch or garter stitch AND in a different yarn. In this case, would it look okay if you picked up and knitted in the same row? Yeah, it would look okay. But, could it look better? ABSOLUTELY! This is where learning to read your knitting comes in handy. In this situation, you might benefit by picking up the stitches (i.e. put the yarn that forms the cast on or existing stitch on the needle) and THEN after the stitches are put on the needle, join the yarn and knit.
In the above photo I demonstrate how to just "pick up stitches". (Note, I did this in the middle of the project versus on the cast on edge so that you could see it better.) See it is literally putting an existing stitch onto a needle.
After the stitches are on the needle, you can join a new yarn and knit the stitches.
What made me think to share this tip as my first QTT? I was knitting on my Range Wrap and the instructions for the second side are to pick up the cast on edge and knit with a different yarn in moss stitch. If I picked up and knitted all in one I was getting an okay look, but I could see on both sides that is was a seam. I ripped it out and went back and picked up and then knitted as two different actions...much better!
Now the seam is nice and neat on both sides of the garment and on the front side it moves easily into the moss stitch. As I was thinking about writing this post, I was trying to decide if it was "worth" it. How often do I come across this exception? Well, right at that moment I went to pick up from a garter stitch piece to then knit up in St st. Again, I played with the approaches and found this other garment also needed the exception. So, I hope you find this little tip helpful.