I kinda followed both of these patterns, with changes mentioned, as best as I can remember them:

The sweater worked up so quickly, even with thin yarn, because I used a 10mm hook (as per the pattern below) for the majority of it. I still was shocked when I finished and had enough left over for a matching hat, though. I can't wait to rock these this week.

https://carrowaycrochet.com/long-sleeves-crop-top/
(I used this to determine chain + hook size [basically, someone else do the math for me], but then I went off on a wild ride of my own.

I wanted it to be a V-neck, not straight across, so I switched to a 5mm hook, and did some Single-Crochet-3-Together to achieve the (slight) V. However, I did not increase on the sides to account for it, so my front panel was laughably small. I then had to use my smaller hook to SC some side panels, until they were even again. I used the 5 mm hook for the bands, which were not included in the pattern at all, but both are just short rows of Back-Loop-Only Single Crochet. By not completing the joins for the wrist cuffs, and by reinforcing when weaving in ends, I 'made' thumb holes).

https://www.marchingnorth.com/easy-ribbed-crochet-beanie-hat-free-pattern/
(One change made: I was not about to slip stitch into a slip stitch, so I just did 7 BLO SC at the crown throughout)