1. Bind mini quilts with fusible tape
Most of us think there are two binding options: 1) Machine sew binding to the front of the quilt and hand stitch on the back, or 2) Machine sew binding to the back of the quilt and machine sew the front. Option #1 looks nicer, but is slow, so I used to resort to #2 despite hating the way it looked. One day I discovered .25" wide fusible tape and I realized I could use it instead of hand sewing the back of my binding. It works like a charm, although I reserve this cheat for mini quilts that wont be handled much.
I sat through a 5 minute demo for this ruler in order to get a free mini ruler at Quilt Con and was unintentionally indoctrinated. If you're going to be cutting lots of strips or similar sized squares, the Stripology Ruler is an undeniable time-saver. It felt a little unwieldy at first (It's about 22" x 16"), but once I got used to it, it became an essential.
3. Stack multiple layers of fabric when cutting
This one may seem obvious, but I didn't start doing this until last spring. It just didn't even occur to me that a sharp rotary cutter would cut through 4 layers of fabric without issue. Now I stack multiple layers of fabric whenever possible.
4. Keep your rotary blades sharp
This goes hand in hand with the previous tip. Nothing slows me down like a dull blade. I used to resist changing my blades because they're not cheap! ...Unless you buy them on Ebay. This seller is my sole source for blades. They're great quality and unbranded, which means you can get 10 blades for $12.95 and free shipping. (For comparison, a 10 pack of Olfa blades costs $65.99 at Jo-Ann's.) I don't hesitate to change blades now.
5. Use Frixion Pens for quick marking and removal
I used to use the traditional blue water-soluble markers for marking fabric, but they slowed me down. The ink frequently reappeared if I ironed my fabric after removing it with water, leaving me to wait for it to air dry. Frixion Pens, which I can buy at my grocery store, disappear instantly with heat from an iron. I love using them to mark out complex quilting patterns, like the center and outermost border of my Rainbow Medallion.