Most knitting disasters are decided before the first stitch. Not by skill, not by yarn, but by the five minutes the knitter did not spend reading the pattern before casting on.
The first read: pens out
Read the whole thing once without knitting a stitch. Not to memorise it — to find the places it stops making sense. Mark every abbreviation you would have to look up, every "at the same time", every instruction that assumes you did something forty rows ago.
Then find the three numbers that matter: the finished measurements, the gauge, and the suggested ease. If the pattern says "worn with 5cm positive ease" and you want the sweater in the photograph, those are the only figures that will get you there.
Gauge, and why it is not optional
A gauge swatch is not a ritual, it is arithmetic. If your stitch count is ten percent off, a 100cm sweater becomes 110cm, which is the difference between a garment you wear and one you reknit. Swatch in the round if the body is in the round, wash it, and measure it after it has dried.
Change needles rather than your hands. Matching gauge by knitting more tightly is possible for about twenty minutes and then your wrists make a different decision.
Notes worth making
Write the size you are making at the top of the pattern in ink, and highlight every number that belongs to it. Cross out the other sizes if you can bear to — it removes a whole class of error.
Note where you stopped: not just the row, but the row within the repeat, and which side you are on. A photograph of the pattern with a pencil mark takes four seconds and saves an evening of counting.
Before the first stitch
Ten minutes at the start — a full read, a highlighted size, an honest gauge swatch — is the cheapest insurance in knitting. Everything after that is just the enjoyable part, which is the point.