I have vision issues and wish someone had told me this sooner, I use a piece of 1/4" Quilter's Tape (just narrow masking tape) to mark repeat cut lines on my rulers.

Is super fast and easy to mark the top, if you spend an extra couple of seconds and put the tape on the bottom, it can also be just a tiny bit of stabilizing influence as well.

Good tip Iceblossom! I quilt/cut/iron sitting down, and am always in favour of ideas to make quilting more accessible. The 'push button' machines were a game changer for me - no more pedal!

I also have a limited selection of rulers - I have a 3"x18" (my first ruler), a 12.5" square and a 6.5" x 24". I do most of my cutting with the last two and can do pretty much anything I want with them (including the string quilt I posted on the last VQW thread). I also have a "Scrap Saver" mini ruler thing that helps with HSTs and QSTs but I have no recollection of where, when, or why I bought it. I found it in the bottom of my regular sewing box when I was looking for elastic for masks earlier in the pandemic. It has markings for alternate 1/8ths" but not 1/4s" so it's only really useful with certain-sized blocks.
I can certainly see the appeal of having the perfect ruler for everything, but at present my quilting budget is pretty limited so I'll save my pennies (and dollars) for fabric. :-)

I think the two most used ruler in my collection are the 6 X 24 inch and 6.5 inch square on. These I use all the time. Over the years I have added others, but those two are the ones most used. They are big enough but not too big. If I could only have 2, these are it. Of course, by now, I have a whole tote bag full. Most I do use on occasion, some I haven't used much at all.

Hmm, I think I will have to invest in a 6 x 24 or similar at some point, but for now, my 12.5" square is doing the job, thanks to tips from Rhonda and everyone else. I am in the same boat that I would rather my quilting pennies went on fabric! I'm also very much a novice quilter, so this and my other large pieces are sent to my local long-arm. She does an amazing job, but it can be pricey... It's definitely not too expensive for the skill involved, but still, not cheap!

Many pattern directions are made with the assumption that you have a 6 or 6.5x24" ruler -- it is very versatile. I began quilting when I was still quite young but right before the rotary revolution and learned a lot before the specialty rulers were invented. It was a common magazine article or the entire purpose of books to teach us different ways to get our desired results. I found I prefer the 6.5" width as it allows me to easily cut 6" finished alternate blocks. It is a really justifiable/needed expense in my book. With that and the square you have you can go far. I do like a 2.5" of some sort as well but that can wait.

I do love me my tools and I love having a wide variety of sizes of rectangles and squares, but find I very rarely use specialty rulers -- mostly because I don't remember how to use them and can't find the directions. But it is pretty amazing what I can do with a couple of angles and a grid! I do believe in things like acrylic templates if you have to cut something like fan or wedding ring or other odd blocks.

My most often used ruler is my 6 1/2 *24. (Just like IceBlossom) It spans the wof easily and would make short work if cutting.

I also suggest you get a square up ruler also. My personal favorite is the Creative Grids 4in1.

You may also want to look up some alternate methods of making HSTs other than the 2 at a time method. There are others that are faster - my favorite is the "strip" method, but you need the CG ruler! You can also make perfect ones on the bias once you know The tube technique, just have a care while ironing.

I bought the new size ruler from Creative Grids. It's 12 1/2 " by 24". I love it. I can cut wide strips from yardage with no V at all at the fold. Have a layer cake cut in no time. It is very big and you may think at first look it is bowed but it will lay flat when cutting. It's been my best ruler purchase in a long time. My favorite rulers are Quilters Select for basic sizes. Missouri Star for template rulers, and Creative Grids for specialty rulers.

I use one of those suction things you can buy for bath tubs to hold on to. I put that on my 6 x 24 inch ruler and it does not slip around when I am cutting. I also have some little round rubber thing on the back of my rulers . These thing really help. Donna Jordan who has a fabric store in Oregon uses a weight that you exercise with and puts that at the end of her ruler to keep it from moving. Good luck and press the fabric after you fold it so it is nice and flat.

Regarding your question about getting the center line. I cut my squares a bit bigger than necessary to give some extra room for error. For example, if you need a 4" finished HST, instead of cutting 4 7/8 squares as per typical recommendation, I would cut 5" squares. I use just a regular ruler of any kind and place it corner to corner and draw a line. I don't think there is any need for a specialty ruler for that!. But as another member said, there are other methods to explore. This basic method works just fine for me.

I have heard good things about the BlockLoc but I have never used it. your square ruler will work just fine as long as you have a diagonal line on it. When you square things up, just make sure the diagonal line is exactly on your seam line, trim 2 corners then turn it and trim the other 2 corners if needed.

congrats on your successful cuts on the folded fat quarters!