Eat some protein and carbohydrates about two hours before you work out, to make sure your body can cope with the demands you’re about to place on it.
Don’t lift the same weights each time you work out. To get stronger, you need to lift slightly heavier weights or perform extra reps.
Try a variety of exercises to keep your body stimulated and guessing what is coming next, or at least vary the order of your exercises.
Your weights workout doesn’t have to be limited to machines. These tend to be limited in terms of movement, as many of them involve sitting down, whereas Kettlebells, a medicine ball and Swiss ball will challenge your core and posture, and therefore help you burn more calories.
Have some protein within 30 minutes of your workout to help you muscles recover effectively.