When I first learned to knit 3 years ago, I ran out and bought all kinds of accessories. Some I still use, others were a waste of money.
Stitch markers. I finally copied the owner of my local yarn shop (LYS) and used scrap yarn in a contrasting color, tied to the needle. The cute little rings kept sliding off the needles or over the stitches.
Needle case. I bought a large one for circulars at the LYS, made by Ashland Sky. It held my needles all right but the yellow plastic size clippies (bought separately) were hard to keep track of when I removed them from the needles I wanted to use. Plus, it was big and bulky to carry in my knitting tote. So I gave it to my daughter and bought a smaller canvas zippered case, similar to a CD holder. It has heavy plastic ziploc-type bags for the needles, with binder rings to keep them in place. More bags can be purchased if needed. It came with stick-on labels where I could write the needle size and length of cord.
I should mention that I only use circulars. My LYS does not stock straights, except for DPN.
Point protectors. The cute little ones shaped like socks were a real pain. They stuck so firmly that they were hard to remove. I now use blue oblong ones I found at Walmart and Hancock’s.
Knitting bag. I’ll be on a quest for the perfect knitting bag forever, I think. Those sold at the LYS are outrageously expensive. I converted a beach bag from L.L. Bean when I was knitting a sweater and needed lots of space. It was far too big to carry comfortably, however. Right now I’m using a black Earth Fare tote bag. Nice, but hard to see inside and no place for my cell phone.
Tape measures and row counters. Buy several if you have cats. I kept losing the round row counters that slide over the needle, so I bought a larger one, oblong, that clicks to count the rows. Available at Hancock’s or Michael’s. Try not to fall victim to the cute tape measures covered to look like sheep or beetles. Too expensive for me anyway.
I also have a regular tape measure for when I need measurements for a sweater or cap. It’s easier than those you pull out of the case.
Stitch holders, buy as needed. I like the softer plastic ones instead of the metal ones.
A small hand-held calculator is great. You can use the one on your cell phone, but it may drain the battery quickly.
Post-It notes shaped like little arrows are invaluable for marking my place on the pattern. I can move it as needed. I also have a regular pad of Post-Its for notes to myself.
When I start a new project, I always make a copy of the pattern so I won’t mark up my book or magazine. It is perfectly legal to make a copy for your own use.
Early on, I created an Excel spreadsheet to keep track of my needles. The columns list size, cord length, and how many of each I have. As I buy new needles, I update the spreadsheet. I keep this in a small binder in my knitting tote. If I am at the LYS and fall victim to some gorgeous yarn, I can tell at a glance if I have the needles desired.
The binder also holds patterns for my WIP’s, as well as notes I’ve made.
I also have a small cosmetic bag in my tote holding tissues, Advil, bandaids, etc.
Hope this helps.