Walk, eat smaller portions
Of course, exercise and eat such that you have a caloric deficit, but those are obvious. Medication that works is a bit trickier - a lot of people buy into diet pills that don't actually do anything/aren't FDA approved, etc. The following are a list of proven anorectic agents:
Oxymetazoline - available OTC in the US as a nasal spray.
Phentermine - Rx only, specifically for weight loss.
Bupropion (Wellbutrin) - Rx only, typically used as antidepressant.
Amphetamine (Adderall, Dexedrine) - Rx only, typically for ADHD treatment.
Methamphetamine (Desoxyn) - Rx only, also typically for ADHD, but has indications for exogenous obesity as well.
I wouldn't recommend amphetamine or methamphetamine for weight loss unless you are very desperate to lose weight or are overweight to a dangerous degree - they are incredibly effective, but cause medical complications. I have tried buproprion myself as an antidepressant and noticed a bit of weight loss, so that one would be my personal recommendation for something that works but isn't too over the top, hehe.
Stick to a good diet and exercise plan and you'll lose lbs fast. It may take a week or two for your body to get use to the change, so don't worry if you're not losing weight in the first week of starting any diet plan.