When I was learning German at school, our teacher had us write down new words in our vocabulary books using different coloured pens for each gender. That way, when we thought of a word, we visualised it on the page in a specific colour. For example, masculine words were in red, so we'd always recall the image of the word 'Tisch' written in red ink in our vocabulary books. I'd also recommend making 'old school' notes with traditional pen and paper: research has proved that the physical act of forming letters and words by hand fixes information in your brain far more effectively than typing.

There are several rules and you can find collections on them if you look for "german gender rules" or "genus deutsch regeln" in a search engine. Some rules are: masculine seasons/Jahreszeiten: der Frühling, der Sommer, der Herbst, der Winter days and months/Tage und Monate: der Montag, er Dienstag, der Januar, der Februar precipitations/Niederschläge: der Regen, der Schnee, der Hagel winds/Winde: der Orkan, der Monsun Nouns ending on -ling: der Schmetterling, der Liebling Nouns ending on ich/ig: der Teppich, der Honig feminine trees/Bäume: die Eiche, die Birke, die Zeder (exception: der Ahorn) nouns ending on -keit, -heit, -ung, -ion, -schaft, ...: die Freundlichkeit, die Freiheit, die Umgebung, die Diskussion, die Mannschaft nouns derived from verbs without the ending -en: der Lauf, der Schlaf neuter metals/Metalle: das Aluminium, das Giold, das Silber, das Blei loanwords ending on -ma: das Drama, das Thema nouns ending on -chen/-lein: das Mädchen, das Schäflein nouns derived from verbs with the ending -en: das Laufen, das Schlafen And so on. There are many more rules. Around 46% of nouns are feminine, 34% are masculine and 20% are neuter (according to Duden). The majority of words ending on -e are feminine, e.g. die Liebe, die Sache, die Macke, die Wiese (exceptions are nouns that have a gender due to other rules - der Schnee, der See, der Tee, der Pate etc.)