I have thyroid cyst what should I do? I also hv mild nodule n goiter.

Size matters. If the size of your thyroid is causing you symptoms of compression (pressure, pain, difficulty breathing or swallowing), then i would recommend that you have your thyroid removed. If any nodule is > 1cm then it should be biopsied. Otherwise, just observe with yearly or every other year ultrasound.
Close follow up. If you have nodules, cysts in thyroid gland , you need a close follow up by your doctor, by exam , scans etc and fna needle aspiration biopsy(s) in suspicious areas to make sure that there is no cancer in thyroid gland.