i usually make sure i dont go over the top on the synths, too many makes it go mental, also keep your fx channels down to what you need, clear what you dont need as that can cause it to clog up a bit vsts play a big part in it, for example albino isnt as intense as z3ta if im making something pretty heavy on the cpu i sequence the intro, then make 3 copies and sequence intro, breakdown then post breakdown if you know what youre listening for you can easily change it, render, then listen and change again accordingly......... long winded but unless you put more ram in your comp its the only way
when mine started going bonkers and crackling, i got a new audio interface which sorted it reet out, before then tho id just save a version of ya tune with all your plugins in, then save another version to work on and render the plugin tracks to audio and insert them, this way you wont have to have the plugins taking up all your cpu, and if you need to change something you can always go back to your earlier version and render agen! hope this makes sense haha