The other guide can take a long time and can prove difficult. Plus he doesn't even give any text guide.
Here is the easy way to get this trophy (text and video guide)!This trophy is very easy and can be done quickly. You indeed have to use the Secret Sauce perk, this is unlocked at level 6 so very early.
Go play the game mode Zombie Rush, preferably the map Voyage of Despair since there's a perk statue in the spawn room. in Rush all purchases, including perks, are free. However in this game mode the game will open the doors for you and this can take a while. That's why you use Secret Sauce on the first perk statue. However there is a slight problem; Secret Sauce will not give you the perks from the other perk machines/statues on the map. So to counter this, prior to the match, go to Create A Class and select Secret Sauce in all 4 of your perk slots.
Once you loaded in, just keep buying from the perk statue for free. Try and keep the final zombie of a rush so that you can walk around without being overwhelmed. Don't use any Elixers like I did in the video, though Always Done Swiftly might be a little useful.
TL;DR: Play Zombie Rush on Voyage of Depair, select Secret Sause on all 4 perk statues, keep buying over and over until you've gotten them all.
Here is the video of me getting the trophy. However, I ended the first rush/wave of zombies because of my Burned Out elixer. So don't do that;