I was given a set of Dembart tool, back in the late 80's I don't recall, how many tools there were or even if it was a full set...
I mix and match Dembart, Gunline and Brownells tool. One thing to keep an eye on is the cut angle, I have mixed 60 and 90 degree cutters and had a mess.
A riffler and a bent needle file will help greatly. Also stay with the same brand of cutters from begining to end of the project and change out heads at the first sign of dullness.
Which covers a few of the mistakes I have made. Also keep an eye on the length width ratio it should be somwhere between 3 1/4-3 1/2 to 1. Outside that range the diamonds start looking funky.
10 LPI is pretty coarse, good for practice though...I started with 18 LPI which is kind of a happy medium, 22 and 24 LPI is very fine checkering and can be a headache, 28 LPI if for those wishing to go insane. I like 20 LPI It is just about right for most checkering. It helps if you have OCD...just kidding!