The pattern I used, called for a change of needles several rows in. On the most part this was problem free but on too many occasions I would find myself knee deep in knitted rows to only find I had forgotten to swap BOTH needles. Argh.
I knit with bamboo. I tried metal ones but my tension goes all funny and my knitting looks like a piece of loose netting. My needles all look the same… I have a love hate relationship with my nails. [Yes, bare with me, I do mean fingernails and there is a link!] Sometimes they grow long other times they refuse. As a consequence I have many nail polish colours bought in the whimsy and feeling of great expectations. Finally another use was born. I have painted the tips of my needles the same colour for each size. This has solved two problems. Now at a glance I can identify the size I need and mid knit its harder to forget to change both needles. Taa daa!
I hope it helps you too.