When you're piecing your patchwork by machine it is important to know how to get an accurate 1/4" seam allowance.
One way is to use your preferred presser foot (mine is the zig zag foot) and measure 1/4" in from right-hand edge of the foot with a quilting ruler. Move the needle by adjusting the stitch width on your machine. I adjust mine to 6.0 to get a scant 1/4" (5.5 for a 1/4").
Each time I sew patchwork I will line up the edge of my fabric with the right-hand edge of the foot.
Another way is to use a 1/4" seam foot. The needle passes through the hole in the middle of the foot so you can't move it much or your machine will make all sorts of noises when the needle bends or breaks when it impacts on the metal of the foot!
Again, measure where the 1/4" falls so you can line up the edge of your fabric with the correct part of the foot.
There are 1/4" feet with guides. I would still measure when I first use one of these feet and then occasionally as it the foot gets older.
Again, the needle passes through a hole in the middle of the foot so you can't move your needle very much or it will hit the foot. To sew the 1/4" you will keep your fabric lined up with the guide on the right side of the foot.
If your machine uses preset stitch widths that you can't adjust try measuring your preferred presser foot. If it is awkward for you to line up the fabric where the 1/4" falls, try using one of the 1/4" seam feet, they can be bought fairly cheaply for most machines.
If you use a different machine at sewing classes and workshops to the one you use at home make sure you measure where the 1/4" falls on each machine. If you do have to use different machines you will be able to keep your 1/4" accurate.
Happy stitching!