All nouns ending in -ung is femininum. Ex. die Beziehung Nouns with two syllables, ending in -e is usually femininum. Ex. die Tasse
There are so many other rules like these, but these are the only ones that I have been able to remember properly and it has been helpful as a beginner here at Duolingo.
All words ending with: heit, keit, ung, in are "die" Die Ewigkeit, die Krönung, die Schülerin, All words ending with: chen, lein are "das" Das ädchen, das Blümlein, etc. All man are: "der" Der Schüler, der Pilot, der Arbeiter
German likes to throw kinks into blanket statements like this, though.
"All nouns ending in an -e are feminine." - Das Ende, unsw
"All nouns beginning with Ge- are neuter." - Die Gesicht, unsw