Preferably 8GB, esp. if gaming.
Uninstall the crap you don't need.
A great program to review EVERYTHING firing up (and to disable if you don't want) when you startup your machine is called 'autoruns', and it's available from Microsoft. It's an indispensable little .exe (no install required) AFAIC. Best way to disable crap there is (other than uninstalling ... sometimes there's sub-programs of things you want installed overall, but you don't want THIS part installed ... like you may want Acrobat, but not the 'auto-update' or 'quick-start' Acrobat programs running at all times ... autoruns lets you disable the sub-programs).
Glad you're having fun. Also, protip when it comes to being short on RAM and gaming on a lappie with shared memory like yours ... lowering texture quality in game settings is usually the best band-aid. also, don't run any MSAA, use FXAA instead 
Edit history
= new reply since forum marked as read