This is my technique for inspiration
1. On the first picture better start with outlining from source pic, dont be shame, its first one - you have to learn car curves not draw "look-paint"
2. Create complete silhouette of car and make it a very dark but not black (f.e. #242424)
3. Using pen tool draw first part, i always start with front bumper, draw whole part, create new layer and right click on your vector > select "Create vector mask"
4. Set complete color of this part, you have two options a) take Fill tool, select color and just fill it b) Go to layer blending options and untick Transparency shapes layer, then click on Color fill and select color (my one)
5. Start with other details, remember - bigger things (shadows, reflections) are first, then you paint over them next items like holes for air etc.
Use Layer folders in Layers menu to keep it well-arranged. Trust me, at the end of the Skyline i had over 140 layers and without folders i wont be able to edit something again
If you want i can create pictures for these steps as a little tutorial, based on my actual drawing of Mazda RX7 FC
