Stitch Markers, Stitch Markers, Stitch Markers .... I use them for even the smallest repeat or to remind me to knit the two or three stitches at the edge of a dish cloth. Even if a pattern only has 4 or five stitches in it, I know immediately if I have made a mistake.
My favorite stitch markers are jump rings. I get them in the jewelry making area of the craft store. They come in all sizes, they are inexpensive (so you don't feel like you have to search for a lost one) and you get a whole bunch of them.
I am DebbieKnits on Ravelery