The Haynes is not vey helpful. It lists a total of 9 earth points but does not give exact locations. 5 of these may interest you: Battery, left and right front and 2 for the electronic ignition ( the last 2 vary according to OEM fit so any car will only have 4 populated) All wires to earth are black so that may help.
A red wire goes to B+ on the alternator (this goes to the starter and from there to the battery still red) and a grey/black to the charging warning light from D+. Earthing is via the body.