Cleaning or simplifying geometry for analysis is an art (and if you don't think so, you've been doing it for too long!).

There are few set rules and the tricks of the trade you normally learn by mistake or by looking over someone else's shoulder. With this blog (and possibly more), I do NOT imply that I know it all or that I can't learn anything new. Quite the opposite. But what little tricks I have learnt over the years growing up with Apex, I would like to share with you.

Defeaturing can also be accomplished using the push-pull tool:

A cylindrical surface can be resized to a new defined radius using the push-pull tool (for other surfaces the value used will move the face by that distance):

When splitting bodies into partitions, the split location can easily be moved by repositioning the triad center:

Partitions can be hidden by changing the selection filter

Dealing with fillets in to-be-hex-meshed solids

Fillets often present challenges when trying to create a hex mesh but there are instances when you wouldn't want to remove them.
In this model example it was convenient to split the gears from the adjacent shaft into partitions using the flat face of the gears, but the fillet creates a poorly meshable corner which can not produce good quality elements:

In such a case, offsetting the cut face provides a better solution (which can be done using flat and curved faces:

Removing many redundant vertexes at once

Redundant vertexes can be removed one by one using the Vertex Add/Remove tool, but selecting all vertexes in one step will remove all the redundant ones (not the ones required to define the geometry shapes).

Mesh seeds or meshing partitions sequentially can be used to manipulate the result

One last thing (for now)

To select the center of any curve (or radius), for which ever purpose, hover the mouse over the edge for a moment, and a little white square will appear at its center for you to pick:

Let me know if anything here is unclear or if you have any other questions (or tips to add here).