Start with the round boundary
Place a stitch marker at the beginning of the round and move it each time you complete a round. The marker shows where a round starts; a counter records how many rounds you have completed. Using both is more dependable than either one alone.
Choose a counting method
You can use a clicker, tally marks on the pattern, or a digital round counter. For amigurumi and other small circular pieces, record the round number before you set the work down. If the pattern says to repeat a sequence, also note which repeat you are on.
Using SkeinHub
When you create a SkeinHub project, you can use round counting and keep the pattern beside the counter. The project stores its current progress, so you can return to the same round after working on something else. The row counter feature supports both row and round workflows, and the amigurumi guide covers the extra checks that small pieces need.
When the count looks wrong
Stop at the end of the current round and count the stitches before changing anything. Compare that number with the pattern, check increases or decreases, and only then move the marker. Changing the counter without finding the mismatch usually makes the next round harder to debug.