I use the Block Maker ruler.
http://www.nancysnotions.com/product...marker+tool.do

There is a video on the page how to use it.

That Patchwork Place square up ruler. it is easy to read no matter the fabric color and is 1/4" increments.

I have a mixture of makes and sizes don't think I have a favourite. I try to. Use a suitable size for the block being squared off is important.

I have one called Quilter's Rule-Square Block Lapboard. It is very easy to read and is "non slip". One of its real advantages is that it has a diagonal line that really helps with the squaring up process. The markings are clear but sometimes I use small pieces of masking tape to mark the lines I want to use. I have used it for years.

Same here.

Literally any ruler can be a square up ruler. I have several I use all the time. As long as you understand the basics of squaring up, you will be fine with whatever square you have. The website gives the method I use, except that I never pull or push the fabrics to make them be square. I find they always want to go back to what they were before. I will rip the block apart and make some smaller seams if the block is too wonky.

http://justquilty.com/2012/08/how-to...sewing-series/

I use this one, too and absolutely love it!

I don't use any particular ruler; I use the marks on my cutting mat to figure out the square and cut accordingly. My mat has a zero line in the middle of the mat and numbers counting outwards from it to the left and to the right, so I can make sure I'm not trimming too much from one side and not enough from the other.

Exception is half square triangles - I use my Bloc Loc rulers to get good corners on those, I butt them against a longer ruler, adjust to proper position, remove the Bloc Loc ruler and cut against the other ruler.

Squaring up a pieced block is tricky. It's not a matter of cutting the block to the size square you want. To keep the points if any you have to have 1/4" past the point. The outside pieces need to be 1/4" wider then the inside pieces on each side.

I use the Quilt in a Day square up ruler too. That diagonal line makes it perfect to square up half square triangles.