The first thing you need to do is unlocking all the nodes. You can refer to somethinglovely.net for all the node placement. And then you should complete your main quest as you'll gain some knowledge and energy from there. Next, you also can unlock all NPC. Simple check your H and look for the missing NPC. You can find the NPC location on BdoCodex. After that, Press H and check the ecology part. This is where it become a lil bit grindy. Select one ecology and complete it. You can hover your mouse on the ???????? part and it will tell you which mob you're missing. 

Press H(default Hotkey) or open Knowledge menu from the escape menu. You dont get energy for every single knowledge you get it for particular topic completion. The easy topics to get done are Character (NPC knowledge - Mix of Questline/Talking/Amity gains) , Topography ( Node expolration/Amity) and Sea Nodes ( Nodes on  Sea and Exploration). Then there is ecology which needs to you kill or gather from monsters to gain their knowledge. You want to systematically go through the Topics and pick and complete the easier ones first while slowly moving to the harder topics.  

The ones mentioned above, plus additional info:  if u do different quest lines on your alts, it can unlock new knowledge. this gave me a huge boost of max energy. u dont need to finish it all the way, but u can do as much as you can and choose different outcomes on certain crossroads. just make sure u dont keep on choosing the same option. 

Hello! For Ecology (H) follow this Youtube Channel as she covers all Monsters/Critters Knowledge in the world of Black Desert. She also categorizes her videos via "map" or "territories" so you can easily follow which mobs to kill and where to find it. Youtube Channel: https://www.youtube.com/channel/UCINtq82n-pIMgaj7b7d53Ug ~Jarette 

Hit H to bring up all the knowledge you can get and go through stuff that you think might be easy. Some topography and character stuff isn't bad (discovering nodes and areas and talking to people) but some require amity to unlock. Ecology is alright too which is killing mobs and getting knowledge.

Hi ALv, you can press H to see a list of all available knowledge. What I did is followed a youtube guide to find all of the NPC, Topography, Ecology locations. I can go over them with you over the weekend if you'd like. DM Discord: Aurafyre#9393.