I've found something that helps me learn nouns and figured I should share it. Most people I've spoken to who struggle with other languages tend to associate the English word with the other language's word. This is problematic because it's adding an unneeded middle man. What you should do instead is associate a mental image of the item.
In other words, don't use "cat" for "Katze". Use a picture of a cat for "Katze". This will help retain the meaning without adding any extra metal steps for each word.