to join scraps of leftover batting to use in a larger project, i cut strips of lightweight fusible interfacing. i trim the two batting pieces together so that the joining edges will match and then i fuse the interfacing strip over the join. it's worked well for me so far. an earlier experiment had me stitching two batting pieces together with a 1/4" seam. that was a terrible idea. i almost broke a needle trying to quilt over that bulky seam. i used this trick on the baby quilt i just finished and in no part of the process was i able to tell that i had joined separate pieces of batting together.
i hate pressing. i've tried to take shortcuts and not press. i've skipped ironing the fabric before i start. i've skipped pressing the seams and just finger pressed. i've never been happy with that particular shortcut so now i always press. even though it blows. for piecing, i finger press the seams open, then press with the iron, then i flip it to the front and press it again.
I started out using spray baste. i like spray baste in theory. it is easier and less back-achey than using safety pins. but due to the weather here i can't really spray baste a large quilt outside a big chunk of the year. and i'm really opposed to breathing in hazardous chemicals when it's unnecessary. so i'm a safety-pin convert.
tape your backing down with painter's tape and make sure it's really flat (not stretched but not too loose) when basting. see? i told you that some of my "tips" are no-brainers, but i really didn't know better or tried to skip that step in the beginning and it was painful.
i place my safety pins about 4" apart. i also remove them as i quilt. i know that you can quilt around them but i worry that i'll end up with weird looking blank spots in my quilting and you have to remove them anyway so might as well do it as you go. it's not that hard to start and stop as you quilt, just make sure that you keep the needle in the down position.
this section will be very short because i stink at squaring up. usually you'll have a straight seamline near the edges of the quilt that you can use as a measure to help you keep the edges nice and straight. i find that after quilting, the edges have bunched in enough that it does effect the size so generally my quilts end up just a bit smaller than i originally intended. this is more of an admission, not a tip. *hangs head in shame*
i have an 18x24 cutting mat. i have a feeling that if i had a bigger one that squaring up the quilt would be easier.
I've tried other binding methods, including a 2 step machine sewn binding and a traditional binding where you sew the binding to the back by hand, and i really prefer the One-Step Binding. Basically you cut 2" strips on the straight grain and join them at a 45 degree angle to distribute the bulk of the seam. then you iron the whole strip in half and then unfold and iron the two ends into the fold. it's the same procedure for making bias tape. you can use (and i own) a bias tape maker but i can never get it to work right and i prefer just ironing it by hand. make sure that you keep your hand far enough away from the steam. silly, perhaps, but i've burned a few fingers in my day.
you then fold your strip in half on the original fold line and iron one more time. the key for me is to iron the strip keeping one side just a teensy bit shorter than the other (so not exactly in half). the shallower side goes on the front with the ever so slightly deeper side in the back. this way when you stitch the binding on the quilt very close to the edge of the front binding, you make sure to catch the back and you don't miss spots. theoretically anyway. i'm still aiming to get better at this one.
also, when you stitch binding on, pin well and go slow. my sewing machine can go 1000 stitches per minute but this is not the time to be a speed demon. go slow and stay close to the edge. i use my walking foot when stitching on the binding as well.
don't work when you're tired, and similarly, stop working when you get tired. i am guilty of this one all the time. whether it's knitting another row, finishing another block, or putting a zipper in a skirt i tend to keep going past the time i should have stopped. and many times i end up making a stupid mistake that makes for a ton of frustration. just stop. it'll still be there tomorrow.
and that's pretty much all i can think of for now. let me know your own tricks and tips--i'm always looking to learn something new.