If you have the hardy hibiscus or Rose of Sharon (Hibiscus syriacus), you don’t really need to do much of anything. If you have the tropical hibiscus (Hibiscus sinensis) growing as a potted plant, then you need to check it all over for pests and then gradually begin acclimating it to the lower light levels it will have indoors. Move it gradually to a shadier location, but do not leave it outside when temperatures drop below about 50F. Then move it indoors to the sunniest spot you have. Keep it out of drafts and keep the humidity around it high if possible. Expect some yellowing of leaves in protest of the move. Reduce watering and fertilizing as the plant’s growth slows. In spring, reverse the process to reacclimate it to the outdoors.