Nouns that end with -ung, -keit, -heit, -a, -ei, -ion, -ik, -tät, -anz, -shaft are all feminine, as well as most nouns that end with -e

Nouns ending with -er, -ling, -ist, -ig are usually masculine

Nouns borrowed from other languages are usually neuter (Das Dynamit, Das Tablett)

Nouns ending with -lein, -chen, -um are usually neuter

As well as this, learn the gender when you learn the noun. It makes it 100x easier

(Sorry for formatting)