How to get lees lag on my minecraft?

I'm new to gaming on minecraft I just got my first laptop which is a windows 8 satellite c55-B with 4gb ram. I have tried everything from lowering all the settings for minimal lag and going to my preferences and stop running other programs that are not needed. I have 100$ right now and I'm able to get more ram but before I dish out money I want to know if there's an alternative way for me to decrease lag. I understand that there are other stuff I can do such as play on peaceful so there's no mobs but I don't want to i want to join servers and play some pvp matches so if someone could please run me through a process to decrease my lag that would be wonderful