Multiple of 4 + 2
Row 1: k2, *p2, k2*; rep from *
Row 2: p2, *k2, p2*; rep from *
Row 3: Rep Row 2
Row 4: Rep Row 1
Is that the box stitch?
This isn't hard but like a lot of things it is kind of hard to tell you.
I don't know for sure where you are at in the pattern when you begin your increases, but maybe that doesn't matter. What you need to do is to be very aware of where you are in the pattern and make the increase be what you need it to be.
I tried this out on a tiny swatch of 10 stitches. That might be a good exercise for you as well.
Sometimes it is nice to have a seam stitch that you leave in stockinette on the right side the whole length and ignore as far as the pattern and the increases are concerned. If you haven't started yet you might try that, but if you are already a ways in you can get by without it. The increases don't need to be at the very edge and it is usually better if they aren't.
On my sample I used a M1 increase where you lift the strand between stitches up with the left needle from the back and work it (as a knit or purl depending on what you need) through the front loop of that strand so you don't get a hole. For instance, if you are at the beginning of a row where you have 2 knits at the beg of the row and need to make them 2 purls this time (if you use an edge st, work it keeping it as St st on the RS, then do this), knit a stitch, then M1 as a purl and then purl 1. So now you have k1, p2 on the right needle and are ready for the next 2 which need to be knits (they present themselves as purls). At the end of the row (not counting any edge st) you will have 2 knits (and you want to inc) which need to become purls as well. So work to the last 2 stitches: p1, M1 as a purl, k1.
I believe observing the pattern closely and making your inc what you need it to be you can always keep exactly in pattern, but sometimes you will have 1 stitch at the end that is in pattern as far as the kind of st it is (k or p) but it won't have its mate like the rest.
So what you need to do is observe your pattern, think of where you are in the pattern and make the increases become the stitch you need and make sure the stitch before and after the increase is what it needs to be to be in pattern. Luckily it is an easy pattern kk, pp, kk, pp and then they offset. Good luck.