If anyone is struggling with a substance use disorder, you are worthy and beautiful and strong. You can do this. It'll be hard, i try not to sugar-coat anything. If you are wanting to quit smoking or just cut back, try smoking one less cigarette a day or a week and keep reducing till you get to 0 or whatever amount you want. Nicotine replacement; patches, vape, work also. In terms of cravings, put strategies in place to distract you from the physical and mental part of cravings. Something like going for a walk or run, writing in a journal or calling someone to talk about your cravings and distract yourself. For anyone with a benzo or alcohol or opiate dependence, please please don't go cold turkey. For alcohol and benzo's in particular, this can be very dangerous. Go to a hospital or visit your local GP for further information. If you have an opiate dependence there's opiate substitutes like methadone or buprenorphine (they mimic how opiates work but don't give you that high). Naloxone is also available. NA is like AA but for narcotics in general. If you want to still use but less, check if there is any safe injecting rooms and safe needle exchange programs near you. Harm reduction is key.
Dependence/addiction is serious, and a lot more than just being hooked on a drug. Therapy is also needed. I am here if you need some guidance for who to contact. I am not a medical professional but have been surrounded by dependence disorders my whole life.