Before tackling your 'good stuff' have a go with different types of knits, cardigans and pullovers from the charity shop which can be a good source for woollies and it doesn't matter if they have holes or pulls for cutting up and trying techniques.
Good to use the swatches made for your knit project for your machine stitch sampling and settings that give the result you want on the real project. (Yep, of course you knitted swatches didn't you, hahaha)
The main issue is to avoid stretching out the edge so a light foot pressure is a good idea.
Find the stitch length and width that works for the thickness of the knit so that the edge is not too stiff or feels like a rope. Each one is different. Try to stitch close to the edge.
Also it's about experimenting with what kit and feet you have.
Pfaff do a
Knit edge foot Bernina offers the
Bulky Foot - check which one works with which machine. Also there's a tutorial on Cra'tsy, but it's not hard to work it out yourself. It can be used for more than knits, overedging etc.
Any foot that has a channel under the foot or a step edge can be used so it's worth experimenting.
On the Janome sewing machines I use I like to use the piping foot for bulky sweater knits or hand knits. I funnel the edge into the piping foot channel and the needle stitches just to the side of it, easy, peasy.
Depending on the knit and how it behaves and whether I'm just sewing up preshaped knitting pieces or using the cut and sew method, sometimes I'll use the sewing machine, sometimes the overlocker and sometimes the chain stitch on the coverstitch machine. When I use the overlocker or coverstitch, if the yarn is fine, then I'll use that in the loopers - perfect match. If the yarn of the fabric isn't fine enough to be used in the loopers then I'll use woolly nylon. I prefer sewing machine or chain stitch over the overlocked edge, except for when attaching bands.
Having sewn a lot of hand knits, various types of bought sweater knits, and machine knits there are all sorts of tips and tricks that you can pick up along the way of experimenting.
The fine, stretchy and loosely knitted fabrics can be the most troublesome, but can look fabulous if you take the trouble with some prep.
Do use narrow cotton tape along shoulders and back neck edges. Sometimes a narrow elastic is used.
Also applying narrow strips of lightweight fusible interfacing to the edges that will be stitched is a good thing. It stabilises the edges for wearing as well as for helping to control the edge when you're stitching.
Experiment with -
lightweight fusible interfacing - cut 1cm wide strips and fuse to the edges.
tearaway stabiliser strip underneath
tearaway stabiliser strip sandwich (on top and underneath) - love this method for controlling compression of the knit and preventing stretch.
washaway stabiliser sandwich - ideal for preventing the needle or the toe of the presser foot catching on a loop of yarn, also helps to prevent the stitches sinking into the yarn and tightening.
painting edges with gloop and letting them dry before stitching (gloop = all the leftover pieces of your water soluble stabiliser kept in a jar and then dissolved into gloop)
Have a play and discover what works for you.