Lost in Lace

I've recently started a new pattern that has a very nice lace pattern.  I start out well, no mistakes.  The 1st time, it was within the 1st few rows of the pattern, my stitch count was off and I had to either make, or decrease stitches to fit the pattern, the second time I made it all the way through the 1st repeat of the pattern and began the second when something went horribly wrong and suddenly my stitch count is off again and there are too few stitches for the pattern.  I've had to frog it twice now and I honestly do not have a clue as to what mistakes I've made to cause this.  Since it occurred in two different sections of the pattern, I know these are my mistakes and not mistakes in the pattern, but I am still at a loss as to what I've done.  Hopefully, with this 3rd restart, I will be able to correct whatever mistakes I am making and complete the pattern.  I will definitely have to post how it goes.  If there are any suggestions, I would greatly appreciate them.