Stephen Travers Art has a wonderful collection of drawing tutorials.

When drawing highly detailed things (fields of flowers, trees, and complex cityscapes) there is a tremendous amount of detail. As it turns out, far, FAR too much detail to actually draw. So how do you draw highly complex detail – without drawing the detail? You draw the effect of detail.

1. Draw some of the key, close items clearly. You need to have some clearly recognizable individual elements of the subject. Draw them of sufficient size and shape to be easily recognizable without any confusion around them – by not crowding them too close together and enhancing their edges with silhouettes.
2. Enhance the silhouettes of the key flowers with shadow/darkness. Fill the elements around some of the key items with shadow to highlight the shape of the individual blooms/elements.
3. As you move back to the background – you keep establishing the key elements (blooms, petals, buds, stalks)
4. Use the direction of scribbles of the darkness to point the eye towards the key elements (blooms/petals/buds).
5. Dark tones come forward, lighter elements are pushed towards the back. So use more shadow in closer elements and lighter elements in the background. To get lighter strokes, use less pressure or use a thinner pencil.
6. Don’t fill all the gaps – move around randomly and leave gaps. You must leave gaps and randomness . Stop every moment or two and see how the wandering of the shadow is going. Is there too much of a grey tangle of lines (too many) – add more dark shadow. If you don’t pay attention, you’ll fill everything in evenly and the giveaway is that it will all be the same overall tone of grey. You want some areas very dark, some light, and some grey.

Architectural drawings

1. Architecture often has repeated patterns. Capturing the repeating-ness is more important the actual pattern that is repeating.
2. Closer repeated patterns should be drawn with more detail than the same repeated pattern far away. Follow the same basic design of the close repeated pattern but make it simpler in the far away repeated pattern – your eye will naturally bring the nearer detail to those elements in the background.
3. If there is a repeated element, draw them all with the same stroke strength and style. This means it’s usually best to do all the repeated elements one after the other to make sure the technique is consistent (pressure, line width, size, etc). This helps you keep them all as symmetrical as possible.
4. For repeated elements that move away from your camera, draw the closest one with much more detail first, then less and less as you repeat the elements further and further away from the camera. Again, drawing the more detailed ones first helps you ‘summarize’ or make a smaller repeated one match easier.
5. Another key element to know that capturing the symmetry of the scene is more important than the details of the elements/decorations. Like before, capturing the flow and pattern of the architectural lines is more important than the actual path it takes.
6. You can also use tone to emphasize form much faster than just using lines

Give his techniques a watch: