First of all, clear out your storage. Remove old files on your hard disk that you no longer use, and clear out your cookies and temporary internet files. If you do not know how to do this, there are many internet tutorials that can help you. Second, unscrew the laptop's bottom case and clean the fan and internal components with compressed air. If the fan is dusty, it cannot work so well and your computer will become warm more often. So remember to clean it. Finally, you can upgrade RAM yourself by taking it to computer shop or doing it DIY. RAM sticks are cheap and can improve your computer's performance greatly.
Hope this helps.