Problems with the cuff

Hi, I’m currently knitting socks—just to be on the safe side for winter :D
Anyway, I’m having trouble: when I try to knit the cuff in knit/purl ribbing, pretty big holes form between the needles. I’ve already pulled the yarn so tight that my fingers hurt, but it didn’t help.

Does anyone have any good advice for me and can help me out? Thanks in advance!
 

Hi,
Do you start each new needle with knit stitches?
I knit a lot of socks too, with both thin and thick yarn, and I always make sure to

.... the first stitches are knit stitches.

 

I’ll have to pay closer attention to that!