At that dosage I would recommend halfing the dosage for 1 week and then half again for another week. Try that.
It all depends on how long you have been taking Seroquel and the dosage. I was able to wean down from 400 to 300 in a week, and from 300 to 200 in two weeks. After that I suggest halving the dosage until you get down to 25 mg, then see how you do. Side affects that are common are stomach cramps, loss of appetite, headaches, sleeplessness, anxiety, and RLS.