Another thing to point out is before you spawn props from the imported  OBJ file is to scale it first.

 I generally do this by bringing in a figure into the scene and scaling it to that figure if you have no dimensions to work from. Then re-export the object with only the last option checked. When you re-import it, the scale will default to 100% and will be at least approximately the right scale in relation to a figure.

Nothing worse than going through the rigging process to find out that when you load it, its the size of an aircraft hanger :-/

And just to reinforce what was said earlier save often.