Is there a sure-fire way of knowing if a noun is masculine or feminine?

There is no such thing as a foolproof way of determining the gender of a noun. However, there are a few rules which are worth learning and which will help you in this way, especially if you are a list learner. The one thing which you need to pay attention to is the ending of the word in question. Indeed, most words ending with -ment, -isme, -al, and -oir are masculine. Conversely, most words ending with -ure, -té, -ion, and -ie are feminine.

Having said that, you should bear in mind that this is not a rule of thumb and that there will always be exceptions. Were you to hazard a guess, I strongly suggest you choose a masculine article or ending since not only are masculine nouns more numerous, but they are also much more common than their feminine counterparts.