Always strive to do one thing extra in the gym. One thing that you have never done before. That could mean..
Using a heavier weight than you have ever used before.
Doing one more rep at a certain weight that you have never done before.
Doing an exercise you have never done before.
If every single day you do one thing extra that will add up to a whole lot over the course of your physical transformation. Just one thing a day can make all the difference in the world.
For instance: Last time you were in the gym you benched 205 for 5 reps, this time you benched 205 for 6 reps.
That's your one thing that you have accomplished. That one thing that your muscles and your body were not used to, forcing them to change and adapt.
Think of what you will bench a year from now if you always follow this rule.
Many lifting programs were developed like a mathematical formula where you add 5 lbs per day, or a certain percentage per day. That's all well and great for a little while, but at some point your gains will completely stop.
The human body is not a machine so you can't treat your workouts like some sort of computer program. Strength gains will come organically with hard work, they will not come on time with some contrived routine.
To ensure you get the most and that you are gaining strength always push yourself to do one thing extra.