I'm LH and was just taught to knit the RH way back in the 60s.
I perhaps have a tendancy to 'pull' the stitches on to the 'knitted' needle rather than pushing them from the about to knit needle, in the same way that I sometimes hold meat with my knife and tug with my fork, as the actions seem to be related to the dominant hand, if that makes sense.
If your friend wants help from other knitters, it will probably be easier in the long run to go with the majority while learning, even if for personal preference they end up knitting left-handedly once proficient.
I've knitted everything from Aran - including dropping wrongly-cabled stitches and re-cabling them up the front of a cardigan, and knitting the 2-ply shetland lace Christening robe and shawl that was published in magazines when Prince William was born.
My dm and I knitted to the same tension, the only difference was that her knitting in stocking stitch was perfectly even - almost like a knitting machine even, and mine slightly less so.
I've just knitted in France with French knitters, and my tension was slightly tighter - could have been stress, could have been due to a difference in knitting technique, but I hadn't knitted in over 25 years, so was fun to hand-knit again.