There are many training aids, alignment aids, devices and gadgets to help with putting. Believe me, I know. I trip over them all the time in my house.
Two of the most important parts of the putting setup are alignment and club head path. If either is off, you will miss the putt no matter what.
One way I like to check my setup is simply by checking my stance and putter head alignment in the kitchen while making Greek chicken, Greek salad and sipping on a red. I’ll use two different alignments on the kitchen tile.
First I’ll set up with my feet on one line, and put a dissecting line in the center of my stance. I can check my foot alignment and club face alignment against the grout lines running perpendicular to my stance.
Second, I’ll set up with the putter face at a four way intersection of the tiles. There I can check the face alignment as well as try some strokes along the line.
I’m a bit of a “swinging door” putter, so the head won’t travel perfectly along the line, but it still helps visually.