Visiting the Great Wall on October 4-5, from near Forbidden City any advice?

Which section are you going to visit? Is it Badaling? If so, you are recommended to take a train from North Railway Station. Although it may be crowded, it's better than queueing up long for the bus 919 at Deshengmen.
From Forbidden City, you can take subway line 1 to Xidan, adn then change to line 4 to Xizhimen, get out through exit E2 and then walk to the railway station.
The train departs at 06:12, 07:58, 08:34, 09:02, 10:57, 12:42... Duration is less than 1.5 hours and ticket fare is CNY6. You cancheck the real-time schedule on this website.
Have a great time~