Going from an area of low information density to high density Consider the following, I've got a mesh already that is in the general shape of my model. However I want to add detail like adding an eye to the general shape.

Example (attempt at modeling bullet bill)



What I'm attempting to do is keeping quads somehow split the edges around the eye area (marked red) and join the two seperate pieces of mesh.

How would I about attemting something like this. I assume I need to split the edges to add in poles at the front and back of the eye area. but then how do I insert quads so that they all match?

In this image its been brought a bit forward from the model just to show the example.

But in general how do I add detail to a portion of a model without adding loop cuts everywhere?
I think there's no scientific way to learn how to do it, at least in my case I'm still learning day after day how to do it, I guess you just need to try how to join, merge vertices, use the knife to create edges, etc... and keep quads as much as possible, then tris if you don't have choice. Actually each case is a particular puzzle.

Duarte has given you links and it explains how to go from 3 edges to 1, etc... I guess it worth a look.

Anyway, to begin I've separated the eye mesh, then I've used the Knife Project tool to print the eye shape on the rocket mesh.