In general, if you want to get stronger, the rule of thumb is to lift hard and lift heavy. However, it's not as simple as that, there are a few more details to this statement that will make your training more effective. You should be training at least 3 times per week, with a minimum of 2 days rest in between. If you are doing this correctly, you will see significant progress over time as your body adapts to the stimulus that you're giving it. However everyone doesn't have to use the same workout frequency, there are variations to this depending on a number of factors.