Lace is beautiful, but it can be challenging to work and keep the stitch count correct.
First, always count the stitches every so often after finishing a row or round to make sure you are still on track.
Second, it’s worth it on a complicated lace pattern to put in lifelines every couple of inches or so, so that if the work must be ripped back to before the mistake, the stitches will not be dropped beyond the point where you want to start knitting againl
Third, work a swatch first, before starting the kniited piece. You can start learning the pattern, make sure it works out, and trust the pattern because you can see it works out, even though sometimes it doesn’t look like that is the case. You can discover flaws in the pattern, and usually figure out what the problem is from other information given and be able to work the pattern anyway. Look at the chart vs the written instructions, see what is missing, look at the multiples, often there are clues.
Fourth, learn how to count your lace properly. Count a yarnover as one, but count a decrease as one also. In other words, if the pattern says k2tog, yo” there are two stitches involved. Remember that a double decrease like SK2P counts as one also. Knowing how to count lace stitches will help you figure out where your problem is and possibly avoid ripping out rows, rather than just a few stitches. Start to visualize your pattern stitch as knitted by looking at the chart. The chart will give you a picture of what your lace looks like.
Have fun with lace, but just don’t jump from simple eyelets to complicated lace, frustration will set in. The more you work with lace, the more you will begin to understand the ins and outs of good lace knitting and counting lace stitches.