This app was mentioned in 7 comments, with an average of 3.14 upvotes
I really like BeeCount! It lets you set multiple different counts for the same project and also lets you set alerts. It's a pretty simple app developed by someone from Ravelry, so it's free and ad free, but doesn't really have anything fancy like anything for charts.
I've used a fair number of them and have settled on Bee Count. Each project can have it's own slot, with several counts. It's free and better than other paid apps I've used.
I would agree with the other comment. If it's all garter stitich, you don't need to count rows.
But if/when you do get to more complicated projects that require you to count rows, I recommend this app. It has a lot useful settings to link counts and auto-reset, which I use all the time for cable repeats.
Interchangable Circular needle set with extra cords. My knitpicks ones come with a cap, so if you need the needles for another project, you screw on the cap and it keeps your work safe on the cord.
Crochet hook for picking up dropped stitches. Also could be used for weaving in ends.
Stitch markers, different kinds. I like the round rings as they don't snag on things, but sometimes I need to move markers around so I use ones that can open. Also need contrasting colours too to mark say pattern repeats vs end of round on a hat/sock done on circulars.
Ruler/ fabric tape measure
Needle size measuring thing (may not be needed now, as some new interchangable sets have the size printed on them). Most double as a ruler/gauge measure.
Ball winder - this thing is great especially when you get screwed up center pull skeins. If you buy yarn in hanks this is a must buy. You might also want a swift to make it even easier when you have hanks.
Stitch/Row counter. I use an app which is AMAZING as it can track all my counters in one place and have different counters within a project. Not affiliated, just a huge fan. I have no idea how I lived without it! https://play.google.com/store/apps/details?id=com.knirirr.beecount&hl=en
I use the BeeCount Knitting Counter to keep track of what round I'm on. https://play.google.com/store/apps/details?id=com.knirirr.beecount&hl=en
It's a pretty good app as you can have it repeat and have different counts within a project.
Before apps, I would just use a note pad and note, or I print out the pattern and cross it out on the paper.
For rounds, I just mark the first stitch of the round with a safety pin. If it's a big project with repeats I use different coloured markers/safety pins for that.
I like BeeCount. =)
https://play.google.com/store/apps/details?id=com.knirirr.beecount&hl=en_US