For mix loudness, an understanding of RMS and Peak levels are needed. The RMS level is more associated with the perceived loudness of a mix than the Peak level. There is also a Perceived loudness level, but RMS, which is available on most DAWs, is good enough for an approximation.
To prevent fast transits from going beyond the established peak output level, a hard, brick wall limiter is needed. Not all limiters are designed to quickly compress fast transits. A good peak value is -0.3 db.
After the brick wall limiter is setup, place a gain VST before the limiter and a RMS Loudness meter after the limiter. Increase (or lower) the gain until the desired RMS Loudness level is reached. For the type of music that I produce, underground Deep House, I usually aim for an RMS of -10.0 db.
If the limiter is working too hard, there is probably an issue with the overall balance of the mix. A good, balanced mix, with proper EQing and leveling, is the first step to having a achieving a loud mix.
In addition to the information above, place a high pass filter on all elements of the tracks that are non-bass components (i.e., snares, pads, etc.). A good setting is about 150 Hz. However, solo each instrument and remove as much lower frequencies as possible without affecting sound of the instrument. Most of aforementioned frequency content is not heard, but it still clutters the mix and lessens the impact of the kick and bass. Also, it makes the mix bus compressor and limiter work harder than necessary.
Furthermore, it is also a good idea to add a high pass filter over the entire mix to remove frequencies below 25-30 Hz.
I hope this information is helpful.