Knit a small TENSION STRIP - BEFORE ever knitting a swatch. Wash and treat it as you would the garment to choose which tension looks and feels the best. ONLY THEN knit your Tension swatch.

TENSION STRIP METHOD: C/on between 10 to 20sts at what you consider is a tight tension fo the yarn in use [example only T4] ; * Knit 10 to 20 rows, make 4 eyelet holes and place markers on sides; CHANGE tension one WHOLE number higher [ example T5] * ; Repeat * to * [increasing the eyelets to match the tension] until you you have what you consider is a tension that is far too loose for the yarn. C/off and remove from machine. Once treated, check the handle and feel of each tension area. Look at the reverse and front rows, to decide area looks the nicest. Then knit your Tension swatch at the tension that you feel is the best for your yarn.

This method is less wasteful on yarn and saves a lot of effort knitting lots of large swatches at tensions that don't work.

I do a small swatch for ballpark numbers, then the back up to the armholes (start on waste yarn, put the ribbing on later). It only takes a tiny bit more time than a large swatch, you can mark it with yarn markers and not only do you get accurate gauge over a garment sized piece, you can check that you like the length and amount of ease too.

I too have made these mistakes...I just finished a sweater with arms for a GIANT. My stitches per inch were fine (the sweater width was spot on) but the length was ridiculously long. After reading this, I went back to my swatch and re-measured. The rows per inch were off (obviously), but I struggle with my swatch being uneven. So, 1 area is 26 rows, the middle is 28 and another area 27. I went with 28! I was wrong. The actual sweater knit was 6 rows per inch. BEWARE! 1 more row per inch makes for a LONG sleeve/sweater!!!! ;+)

I did many of this mistakes..... Propper swatches make better fit. Today i make propper swatches. With marks and stitchruler, And count stitches. Dress/wash/dry like the intended garment, ( hanging, too) For tuc and drapy yarn i even double the swatch... but still the garment behaves different than assumed some times. Gauge changes from wash 1 to wear and wash 3rd time, too.

I like this!