Put Points into Intelligence
Intelligence is an incredibly useful characteristic for your Fallout 4 character to have. Not only does it unlock some rather handy points as you progress through the game, but the more points you pour into Intelligence the more XP you’re going to get from any activity you complete that normally gives you it.
A recent Reddit post has calculated the effect that one additional point into Intelligence will have on the amount of XP that you get. This rather brilliant calculation has worked out that for every point you put into the Intelligence skill, it works out at about a 10% increase in the XP you receive. Therefore it’s simple enough, if you need more XP and faster, focus on putting those early skill points from levelling up into your intelligence characteristic.