Do you get lost every time you put your knitting down if you are doing anything more complex than stocking stitch or garter stitch?
If you do you suffer from "linearitis". This sad disease plagues many knitters but is more prevalent in the novice.
There is no cure, but there are ways of managing this condition. You need to learn to read your knitting instead of the written or charted stitch pattern. We learn to read from left to right in a linear fashion and knitting patterns that are written out in words encourage this tendency. Charts are better at providing a visual representation so that you can see what happens below and on either side of the stitch that you are working. Unfortunately most of us still use the chart one line at a time often using a post-it or a ruler to mark our rows. You can practice while you are knitting your swatch (you are knitting a swatch of course?). Once you can read the knitting, finding and correcting errors becomes much easier but it does take practice. You will also find that incorporating more stitches as you increase up the edge of a sleeve or the loss of stitches at a neckline or underarm is no longer be a cause for tearing out your hair or your knitting in frustration.
As you work the swatch don't just construct each stitch one by one take note of how it relates to the stitches in the previous row(s). Take the time to be aware that the yarn overs are moving over row by row one stitch at a time in a diagonal line to the left. Notice the the purl on row 4 is always made into the yarn over of row 3. Every stitch pattern will have different relationships so start to learn this on simple patterns just like when you first learned to knit you knew if the "bumps" were facing you it was time to purl on stocking stitch.
When you get to the end of the row and you have stitches left over you should go back to the stitch pattern and start at the beginning of the row on the right hand side comparing each stitch one by one to the pattern until you find your error. At that point tink back and make your correction.
So start practicing now. Your knitting will be better because of it!