I tried many ways. The starter way is farming Emeril but it isnt the best and fastest way. Farming pearl/gravito ball/venom sac since all 3 cost about the same I just include them in its also not the fastest way.
http://steamproxy.net/sharedfiles/filedetails/?id=746819108
I used to farm it.

Now the fastest way is looting freighters. First find a space station with +100% price for titanium.
Sometimes freighters spawns outside the space station which is good. Fly to the freighter and locate his weapons. Attack from the bottom there are usually less weapons. Then destroy the weapons first. You will get 1 or 2 wanted lvl but let the cops alive otherwise more spawns. If there are 2 cops kill one just keep in mind at least 1 have to be alive. Now have a fast movement repair your ship and aim. My ship set up only have the base shield just upgraded weapons.

If the freighters are very far away its also doable. When you finish with looting and want to fly back to the space station fly abit away from the freighters and kill the last cop now you can use ur booster to fly back to the space station. Sometimes if you´re lucky they even lose you and you lose the wanted lvls.

I would suggest you to delete the irons so you can take more valuable stuff.

The good thing is you dont need plutonium cause your lifesupport doesnt go down inside yout ship and space station also it wont consume fuel if you start in a space station. You dont need to keep a stack of Thamium9 cause there are plenty outside, if your booster fuel gets low destroy a few meteroids. Also you dont need any kind of exo suit upgrades cause its useless if you do it this way you can see in the picture I dont have any.

http://steamproxy.net/sharedfiles/filedetails/?id=747406953
http://steamproxy.net/sharedfiles/filedetails/?id=747406908
One pic from my exo inv and one from ship inv. Titanium alone sells for more than 1mill not counting copper, iridium ect... As u can see i have 25,8mill there.
http://steamproxy.net/sharedfiles/filedetails/?id=747407638
Now 27,8 mill after selling all loot from freighters. Thats 2mill in less than 10min. Even more if u dont have the atlas stone like me there.

I set a timer it took me about 7min to fill my 48 exo slot and 40 ship slot up including repairing/deleting irons/flying and selling ect... I start the timer when I take off inside the space station. And I tried it without the Atlas stones I made 2,5mill per run.

http://steamproxy.net/sharedfiles/filedetails/?id=748893630