On this page, I will list the different forms of the Gaelic article in a manner that hopefully will help you to get it sorted in your head. If you have ever had Latin classes, you are probably familiar with rattling off tables of paradigms. For Gaelic, the most important piece of advice is: don't do that, ever. Just don't. Trust me.
How the Gaelic article works does not depend on case/gender/number only, but on the first sound of the following word. So, always study the article together with a noun example, and group them by sounds. Sounds are important! I can't stress this enough.
In the following, I will group the article forms according to sound patterns. You will see that the same pattern comes up more than once for different cases/genders/numbers. So, for example, if you know the pattern for basic feminine, bingo, you're done studying for genitive masculine case and prepositional case for both genders as well! Buy 1, get 3 free, now is that a great deal or what?