I'm a new knitter. Would you recommend I start with larger needles, or smaller ones?

Go to the public library and borrow 3 or 4 books on knitting. Get at least one that has really good illustrations, one that has really good written descriptions, and one from the children's department -- especially if you're no longer a "children." They tend to have simpler projects than grown-ups' books and really clear instructions.

Borrow all 3 or 4 of them. Read through them and see which ones make more sense to you (if you're an auditory learner, the descriptions will work best; if you're visual, the illustrations will.) Then, pick a project at the beginning of one of the books -- stick with something small and easy to finish, like a cell phone case or a small bag. Read through the pattern for that project. It will tell you which size needles and which type of yarn to buy.

Chances are strong that you'll need medium-weight (worsted, 4-ply, weight group 4) yarn. That works well with size US 8 or 9 needles. I suggest starting with a light color. it makes it TONS easier to see your work. You can find and fix mistakes much better on light-colored yarn. It's best just to plan on making some mistakes when you're learning something; it makes it easier on your ego hen you do make them. Save the black and navy for your next project, but start with a lighter color so you can see what you're doing.

I just started learning again. I knew how to knit when I was a kid but I've forgotten it since.

I am using 3.75mm needles. I think that's 5 in American sizes. I had thicker ones but I felt the yarn was too bulky and the needles were too thick.

Most people are comfortable with medium sized needles (7 to 9) and worsted weight yarn to start.

Don't use needles too big. I agree, stick with medium size needle