Providing you fly visually there is no reason whatsoever why you can not follow an ILS. But what will you achieve by doing so? Firstly, there is the distraction. Then there is the looking out vs looking in and then lastly, there is the difference in technique. A visual pilot would typically set speed by attitude and ROD by power. When flying an ILS corrections typically start by using elevator to maintain the glide (which is fixed to the glideslope) and power to control the speed. Eventually it is still a power plus attitude equals performance equation, but the way yin get there is difficult.
Learning how to fly an ILS by yourself will probably lead to poor technique. So how can you start by yourself? Firstly learn to trim "gram perfect" and by that I mean whenever you let go of the stick the aircraft will fly for minutes doing whatever it was before you let go; same speed, heading and altitude. Now learn the magic numbers for your plane. At 2,000' your plane will require X degrees of pitch, Y rpm and will deliver Z knots. Learn the same at 3,000'. Now learn the numbers for different speeds. Now do the same for descents and climbs so you can deliver a set ROC/ROD at various airspeeds. Do the same for different configurations. It may seam over the top but if you can get the aircraft to do exactly what you want just by setting pitch and power, learning to fly on the clocks will be a doddle because you won't have to think about flying. It will give you the time needed to think what you need to do next and where the aircraft will be in the next few hours, minutes and seconds. Now you are ready to start learning to fly on instruments but you will also be a better visual pilot.
PM