Hey Chirag, you can try remembering these sentences from Duo's lessons. Some examples - The cat drinks the milk => both "cat" and "milk" are feminine nouns. The cat eats the mouse => both "cat" and "mouse" are feminine nouns. Öl und Salz => both are neuter nouns.
I have made up something of my own - cheese, cake, wine => masculine nouns tea, coffee, sugar => masculine nouns egg and bread => neuter nouns fruit, vegetable, animal, pet => when these nouns come up, think of them as a GENERAL class or a COLLECTION or a MASS NOUN and therefore, neuter nouns.
If you find the above method helful, build up on the above list and then try to internalize from that list.
Hope this helps !
The definite article "the" developed out of the demonstrative "this, that", and in German they're still the same.
In Old English, they were the same as well, and you had genders and cases -- the masculine gender se turned into þe and then the, while the neuter gender þæt became that. So English split those two up when it started shedding genders and cases, but German did not.