There's a few things I've learnt for how to make your models work with Mimic. These have been tested with Poser 6.0 and Mimic 3 Pro.
Symptom: Mimic reports an error message when loading a project. "This OBJ file has polygons that are referenced to multiple groups. As a result, may not work properly in Mimic."
Solution: Your model has overlapping materials. You might be able to fix this by selecting the Grouping tool from the editing tools menu and deleting the additional material or you may need to create an obj file for your figure and then use an obj editor to remove the extra material.
Symptom: Props such as hats, specs, beards and hair expand or shrink when the character is loaded in Mimic.
Solution: Its likely that the prop was rescaled in poser, Mimic does not support that. From Poser, export the prop as an OBJ ensuring that the Morph Target option is de-selected. Delete the origional prop and re-import into Poser at the correct size. Re-position and re-attach in hierarchy.
Symptom: Character's lips don't move in Mimic preview but works fine when pose is exported and transferred.
Solution 1: Your character does not have the appropriate morphs such as OpenLips, Mouth O etc. If it's something like Victoria or The Freak then you can add these in with an "injection" file.
Solution 2: Newer versions of Poser support external binary morphs (to make the file size smaller) but Mimic does not support that. Under General Preferences, Misc, uncheck the "use external binary morph targets". Also unselect the use file compression as Mimic does not support that either.
Symptom: When rendering a video from Poser the sound is not quite in sync with the lips.
Solution: Delete the audio from the file in Poser. Render the video without the sound, use a video editor to put the sound back on.