So far I’m able to run games from most games on medium/low settings. I’d like to play on medium-low settings. The specs are as follows:
Planning to go 8GB for the RAM.
I agree with the others. It only makes sense to add ram beyond 3GB if you are using a 64 bit version of Windows. However, since games are usually not played in a multitasking environment, that extra RAM probably won't make a difference (or not much difference) anyway. A better graphics card would, but that's probably not an upgrade option on your laptop.
Adding faster compatible RAM may increase frames per second a little, if at all, but not the quality of games. A better CPU would help some, but a better GPU would help even more with the quality you can play the games. Unfortunately, the CPU and GPU generally are not replaceable, except on certain gaming laptops in which the GPU is removable and replaceable. About the only thing you might be able to do is overclock the GPU and possibly the CPU, but not all laptops allow users to overclock the CPU or GPU. If you are able to overclock your computer, don't expect a great deal of an increase in performance, but do expect higher levels of heat and lower battery life.
As Hovsep said adding more memory only makes sense if you have a 64bit operating system.
That aside your biggest bottleneck is probably the graphics card. Speaking performance the Geforce 520M is in between the Intel HD Graphics 3000 and the 4000 series – both integrated graphics solution. It's ok for office work and standard multimedia but not really suited for games.
All in all upgrading the RAM will mostly only improve multi-tasking which you really don't do while playing games. Or in other words: Any game demanding more than 4GB of RAM will barely or not run at all with that graphics card and probably also the Core i3.
if you have a 32 bit Windows OS, your system will not be able to recognize more than 4 GB of RAM. if you have 64bit Windows OS then you can increase ram to 8GB. Geforce 520m is a Geforce 520m adding more RAM to your already existing 4GB DDR3 will not give huge gameplay advantage, but if it is possible to overclock then you can gain some FPS.