I did one illustration like this. It includes thin curved lines. I took lot of time and patience to create this one. But the end result is looking a bit cluttered. I'm expecting very smooth curves. How can I make these curves smoother in Illustrator.
There certainly is room for improvement in Adobes anti-aliasing routines. Adobe is not a big DSP shop and really does not need to follow the latest in the development of algorithms. In terms of what science tells us one could do better. For example one could use Lanczos filtering on the multi pixel sample. In addition filtering should be done in a linear color space, then converted back to nonlinear sRGB for example.
Image 1: Art optimized done in Illustrator (left), and linear Lanczos filtered (right)*
Now adobe seems to use bicubic filtering which is almost comparable to Lanczos overall, which one you prefer is ultimately up to you. The non linearity in filter spreads the lines wider and make them look pixelated. Bear in mind due to the fact that adobe uses the non corrected preview then your lines will be a bit thinner, once corrected.
* used following imagemagick command on a 1600% image with no AA:
convert artopt2.png -colorspace RGB ^ -filter Lanczos -resize 175 ^ -colorspace sRGB ^ out.png