A well-balanced arrangement and mix will determine your track's loudness potential. The "throw a limiter on it" type of advice will do your music more harm than good if you don't understand what affects that limiter. The mixes with the highest loudness potential are those with the cleanest arrangements, meaning those without multiple elements fighting each other for space in the frequency spectrum. And the most important area of the frequency spectrum, as far as limiters are concerned, is the low end. The cleaner and tighter your low end is, the better, as low end eats headroom for breakfast, and if you find your mix is pumping and/or distorting, a kick drum, bass, low synth, etc. (or a combination thereof) is probably your culprit. A lot of people layer three low drums with sub bass, cello, and miscellaneous low synths and then wonder why their mix is a pile of mud that distorts the second they bring down the threshold on their master limiter. Figure out what elements are essential to your arrangement and mute the rest. This is a necessary skill for any great producer, regardless of loudness concerns. One great way to hone in on your low end at the mix stage is to solo it with something like the free Isol8 plug-in. Check those lows and low mids. Turn the mud into something focused via EQ, transient design, dynamic EQ, compression, etc. Your headroom will thank you. Also, Google the Fletcher-Munson curves.
With that said, loudness is absolutely the last thing to worry about, and everyone's music would benefit from less focus on it.