Use the same ruler to cut all
the pieces in the project, so everything is measured against the same standard. I only use the lines on the mat as a GENERAL measurement, not to measure accurately. For example, if I need 2 1/8" for a binding, I measure with the ruler. If I need about a 2" piece for paper piecing, I can use the mat.

Rulers, rulers, and rulers. I use the 5 X 23 inch ruler to cut my strips. Then smaller rulers to subcut these strips into the pieces I need. After the block is pieced I use a square up ruler.

Ditto on that...fabric edge on mat board line, then place ruler on fabric and line up..

I used to use the lines on the mat, then I read to use the ruler. Since I started using the ruler my pieces are more accurate. I also use the June Tailor Perfect HST ruler to square the pieces. That has made a huge difference.

God only makes perfect, things that are not perfect to you just put character in the quilts

If you have a Bernina, I highly recommend the #57 foot with a guide on it. It's dreamy. And when you need to pin certain junctions, do it.

But I suggest NOT changing anything midway through a project. :-) I had taped a seam guide to the bed of the machine, then I bought a foot with one attached, and there was a difference between the two.. So I am saving the foot for my next project.

I had to learn to Press not Iron. I ruined several quilt squares this way. Even if you cut perfectly(NOT ME) sew perfectly(STILL NOT ME) you can stretch or mess up your shape when you iron. Lesson learned. I didn't use to press or iron at all but it made a difference in a warm wishes quilt i tested it on. Then i ruined my first diamond star block. Hopefully I will do better. I learn so much here with so many great people teaching!!!

It is definitely a learning process. I am totally self taught, so I have made every mistake that can be made. But I heave 17 grandkids to give quilts to, and I see improvements with each one that I do.

i use my cutting mat , and iuse it for all my cutting ,just like the comments above , it is what you are comfortable with and use it to measure everything !