Are there rules regarding gender on neutral items?

[degausser_]

I'm getting confused by what is "female" and "male" when it actually has no gender.

For example, I just got a translation wrong because I used the wrong gender for salt. I feel like I just have to guess each time.

I have picked up that words ending in -a or -as are usually female and -o or -os are usually male (apparently there are a few exceptions but I'm yet to come across any) but with a word like "sal" how can you tell?

[rspreng]

Sometimes you can't, you just need to learn them. Many nouns have no obvious gender. There are general rules like --dad, --cion, and ---sion words are feminine, and --ma words are masculine, but you either need to just plug away or consult a decent Spanish grammar book (or www.studyspanish.com ) and begin to learn them.