When learning how to mix it can be tricky to manage levels of various tracks without clipping the master output.
Instead of using limiters or bringing the master fader down , set your loudest track to -12db, such as a kick drum if dance music or a vocal in other genres for example, and work around that. By the time you finish your mix you should find that you will have around -6db headroom, which is ideal for mastering.
Another technique to achieve this is to use an analyser, such as Voxengo Span, and change the metering to K12. Use the 0 on this meter instead of your DAW to balance your levels and it will also help provide enough headroom.