The following settings are recommended up to NX 11 and CATIA V4.2.5 (Dassault).

NX – System

• Delete blanked elements before preprocessing.
• To transfer colors of assemblies the colors should be set and saved with the individual components, not the assembly.
• Note that NX uses the radius of a "tolerance tube", other CAD Systems like CATIA V4 define "tolerance" as the distance between two points.
• Select Analysis -> Examine Geometry -> all options -> all elements (up to NX2). 
• Select Analysis -> examine Geometry -> Set All Checks (up to NX8.5) The marked elements are likely to cause problems with data exchange, depending on the messages as explained below:
• Severe errors:
  data structures, consistency, face-face intersections, self-intersections
• Might cause problems:
  tiny, face smoothness, spikes/cuts, edge tolerances
• Without negative influence on data exchange:
  misaligned, sheet boundaries, edge smoothness

NX - STEP Preprocessor

• Start the external STEP processor with File -> Export -> STEP214.
• Select Data to Export and define the options:
• Object Types: One or more of the options Solid, Product Data, Surface, and Wireframe (depending on model).
• The default tolerance value in menu Advanced -> Parameters -> B-Spline Aprx. Tol. of 1.01*10-5 mm can cause to very large STEP files and should be reduced in such cases(recommended value: 10-3 mm).
• Recommended is to use the default settings in menu Translation Control (Tolerant Modeling).
• Special characters in the filename of the STEP file are not allowed. The model will not be exported.
• Validation properties are supported.

STEP File

• In the filename syntax special characters (especially / * % ) or umlauts must be avoided.
• The STEP file extension must be changed to *.step.

CATIA V4 (Dassault) - STEP Postprocessor

• Identical curve tolerance should be set according to desired model space. (default: 0.1 corresponds to 10m model space)
• Recommended settings in declaration file:
• st1cat.EXACT_SOLIDS_CREATION=TRUE (creates SOL instead of VOL)
• st1cat.TOPOLOGY_HEALING=TRUE
• st1.cat.CATIA.REPLACE=TRUE
• The log file filename.log gives hints about translation success. Check for converted/failed STEP entities in the summary at the end of the file. 

CATIA V4 (Dassault) – System

• Each component of an imported assembly is located in a separate workspace.
• The master workspace shows the whole assembly.
• To remove the text added to the model use: TEXT -> ERASE -> *FAC+*SUR etc.
• Shaded view is helpful for a first impression of model quality.
• With IDENTIFY look for received SOL, VOL or SKI.
• Use CATCLN.