There are quite a few different techniques for making a nice looking edge on things like the garter stitch you are doing here. I think they are quite nice to do on a scarf or something that has an edge that will always show. But I don't think they are actually needed on garter stitch if you get a nice edge in your knitting; they are an option. Also I don't like a "special" edge if I am going to seam.
To get a nice even edge I find that after I have knitted the first stitch, when I insert the needle into the second stitch, before I yarn around or anything I give the working yarn an extra little tug. Then knit that next stitch. I think that is my secret, but I'm not sure, it all happens so automatically.