When finished, check all the instruments that they sound fine and your templete in GS3 stays the same if you start playing in the sequencer.
Now load the MIDI file you saved before, select a track, and COPY and Paste into the empty templete, on the track where it should go. Do this with all the tracks, then save this templete as a work-file. If you play this, it will sound bad, because all the mixing controls are missing. Now comes the fun of going track by track and set your Volumes at 101 in the sequencer, set your velocities in the GS3 Mixer window with Controler 1 to about 65, and your main tool for dynamics,Control 11 to 60 also in the Mixer window. As you are soloing the tracks, you can draw controler curves of Controler 11.