Consistency is really the key to success when it comes to any goal you may have, especially losing weight. Changing your diet for one night or working out sporadically when you feel like it won't cut it. If you want the results to happen, you're going to need to be informed on what's best for you and your body, patient (you more than likely won't lose 30 pounds in one month), and most importantly, consistent.
If you've decided that weightlifting is the route for you to lose weight, you're going to want to make sure you adhere to this strength-training advice. First, it's always best to go into a strength session with a plan: the workout you're doing, why you're doing it, and what you'd like to get out of it. Second, if your goal is weight loss, you need to lift heavy and frequently.
Every body is different and will adapt to strength training differently, but I typically advise training three to five times a week. If you're a beginner, start out with three strength sessions a week. As you get acclimated, begin to increase the amount of sessions per week. Beginner or novice, be sure to space out the muscles groups worked to avoid overtraining and being overly sore. A great starting point is to break up your workouts into specific days, for example:Monday: legs and core Tuesday: chest and shoulders Wednesday: cardio Thursday: back and arms Friday: total body conditioning Saturday: yoga or mobility Sunday: rest
If you aren't sure where to start with programming, this four-week beginner workout plan is a great resource. Be sure to hydrate, replenish your body with nutrient rich foods, and sleep.