I just perform simple offering-rites. I invite the divinities of the Pre-Christian, ethno-linguistic group my tradition is focused on (in my case, The Aesir, Vanir and Rokkr of the Teutonic Europeans) or spirits like my ancestors or wights. Further, I use symbolic items or depictions specific in that culture (the runes, Thunor's Mjolnir, deity representations, drinking horn etc.). Then I give my offering, do a rune casting inviting that I know information which I may need, and invite the gods to stay or leave at their will. The offerings I use vary. I've used water, rice, bread, incense, even my own blood (via sterile lancet, of course).
As far as how I conduct myself in ritual, I agree that there's a correct way to approach gods and venerable spirits, and to go astray from the correct way would be hugely devastating to the practitioner and greatly offensive to the gods. This correct way is respectfully. Anything else concerning "correct" ritual etiquette is getting trapped in orthodoxy, and orthodoxy obsession is for monotheists, and gets into the discussions of beliefs, which the only real belief one should have to be a pagan is a fundamental, core belief in the gods, maybe as superior to humans (why call them gods if they're not?). Other than that, like what does it matter what the practitioner thinks will happen after he or she dies, where the gods come from, about the reality of cosmology or anything else? If the gods disagree, they're more than capable to let us know, and as far as I know, they're not saying anything.