It kind of depends on the situation, but my preference is to knit into the front and back of the stitch. Or I do a "make 1", lifting up the bar between two stitches onto my left needle and knitting into it.
Kimberly: blogging wife to Todd and work-at-home-struggling-with-work/life-balance adoptive mama to Adam (2005) and Leah (2008)
depends on what it's for If I want a lacy, decorative increase i do a yarn over. If I want a hidden increase, I do a lifted one (picking up and knitting the stitch below where I want to increase) If I want a run-of-the-mill, slightly decorative, I use knit front and back. If I want paired increases, I'll do a m1, picking up the bar between the stitches (twisting the one on the left side so it mirrors the right.)
you can, but it's a little tougher to get the needle in the back purlwise. You really have to jam it in, LOL! basically, you purl normal, then you bring the right needle behind, and UP into the stitch.