Choose the right friends
You've probably heard this a million times but sometimes your best friends aren't the ones that you should study with. Make sure the friends you choose are ones that you work well with and won't get distracted by. Also it really helps to choose friends who achieve similar grades to you so that you are on the same wavelength as each other. Lastly, before meeting up, ensure you and your friends have the intention to study so you don't go off track and socialise.