I've started a series of isometric tutorial videos, showing how I draw various pieces of dungeon architecture. So far I've done some stairs and a set of arched double doors.
I'm using graph paper from Incompetech, specifically the "isodots", with the dots set to light blue. Using cyan dots lets me pull them out easily with Photoshop (using a black and white adjustment layer with the cyan slider set all the way to white).
The basic points I cover are:
- block out the 3D space the object is going to occupy
- ensure you're rigorously following the isometric lines - all drawings are flat, so this is important to reinforce the impression of three-dimensionality
- finding points in 3D space often happens by finding the intersection between a vertical and a horizontal line (as with the stair creases)
- texture adds character, but must also follow the isometric axes or you'll quickly spoil the 3D impression
- circles are tricky - as with other shapes, first draw the square tht the square that the circle occupies, then draw it as four separate arcs
- draw your objects from the front of your dungeon to the back so you don't accidentally
- draw in pencil first (ideally blue, so you can use the same PS trick to remove it without having to erase)
- use a waterproof pen, so you don't smudge your ink
- use thicker lines to indicate depth changes between objects
Hope it's useful!