How about a little more information. Type of smoker, smoker temp, what IT are you looking for? Doing an hour or so wrapped in a cooler after taking off? Things like that.
Many people here will try to help you out, this is absolutely the best place for information and help, some real long term experts here.. We each have our own particular ways, but as a whole they are similar. Many of us are constantly very fine tuning, but most of us are very consistent with great briskets...
I smoke my briskets at 225 till I get 195+ IT in the thickest part, I am using a very low flow electric smoker that does not dry the outside much, so I do not foil until I put it in a cooler for at least an hour, two if I have time, before slicing.
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I was having a similar problem you are describing and found I was not smoking long enough to get the IT temp high enough for the meat to get tender, I thought I was drying it out, not so. I also was not letting them rest long enough in a cooler after pulling them off the smoker. These are two key items for brisket in my opinion..
Yes, a little different cut of meat each time, but all of them are very close to perfection for our taste..
With some information and practice, you can be consistent also.