A sensible order to work in

This is a suggestion, not a rule. It follows from what the tools do: deleting a part costs nothing in quality, so delete first. Reducing a mesh costs detail, so reduce only what you decided to keep. And there is no point in simplifying a part you are about to delete.

1. Open the file and look at it. Read the totals in Properties. See How to read the numbers.
2. If the model lies on its side or sits far from the grid, stand it up with Align to floor.
3. Find out where the weight is: open Heavy parts and press 4 for the heatmap.
4. Remove what nobody will see with Select hidden parts. Isolate, check, delete.
5. Remove small hardware with Delete small parts, if the model does not need it.
6. Close holes with Fill holes.
7. Replace fasteners and other filler parts with stand-ins, using Smart fit.
8. Reduce the heavy parts that remain with Decimate, or bring the whole scene to a number with Fit to budget.
9. Tidy up: Remove empty parts and Delete empty groups in the card Auto cleanup.
10. Look at the whole model again in the normal view (1) and in clay (5). Open the Optimisation report to see what you saved.
11. Save the scene, so you can come back to it. See Save a scene.
12. Export the file for the program it is meant for. See Export.

Habits that help

• Check before you delete. Isolate shows exactly what a tool has selected.
• Work in steps and look after each one. CtrlZ takes back any of them.
• Save a scene before a drastic step. Your original file is never touched, and a saved scene is a second safety net.
• Stop when the number is reached. A model that is lighter than it needs to be has lost detail for nothing.