This is important and maybe Shane65 you aren't familiar with. Let's say you're downshifting from 4th to 3rd at 50 mph, when you depress the clutch, you gently press the gas pedal to raise the engine revs to approximately what they will be when you're in 3rd, as you downshift. That's 'rev matching' that way you're not putting a strain on your synchros. It takes a bit of practice to get the hang of it. Pretty soon it becomes second nature to do this.