Well that sounds great, and don't worry about it sounding simple - we all have to start somewhere.
It's got to be hard to strike that balance when learning for your self, becaus eyou haven't got a teacher with months of planned out lessons!
But as a previous language learner I'm sure you will have picked up on the tricks before, its just a matter of appliing them to new material.
I found this to add to my point

HORTENED FORM OF ADJECTIVES
The following adjectives drop the final -o when they precede the noun
they modify: bueno, malo, uno, alguno, ninguno, primero,
tercero. (No change is made when they precede a feminine noun or nouns in the plural.)
un hombre bueno (a moral man)
un buen hombre (a good man)
The words grande and ciento lose their final syllable when they precede the noun they modify.
una gran ciudad (a great city)
cien libros (one hundred books)
Hope that helps!!