Here's an obvious-in-retrospect trick for learning noun genders that I've surprisingly never seen elsewhere.
The usual advice is either to associate each gender with a location (Dominic O'Brien), or to associate words respectively with a man or a woman.
But you already have many ready-made associations for each gender -- every word you already know the gender of!
So if I want to remember a new word, I just need an image of it with any word of the same gender.
In practice, I mostly build composite images with several words. For example one of my images for Geman neuter nouns is a castle (das Schloss) made of salt (das Salz) on a river-bank (das Ufer), dissolving into the water (das Wasser).
This began with me knowing the gender of water, and associating castle with it. I've then gradually added other words as I learned them. Suppose I want to learn automobile (das auto) -- I just have to fit it somewhere in here, or into another of my neuter images.