So I finished modelling my mesh for a spaceship and moved on to texture painting it. The problem is that I'm following the design of an image in the background and I cannot see it while painting as the mesh is black. Is there some way to make it transparent so I can see the image while painting or...?
Texture Paint with Brush Mapping Stencil.
In texture paint mode open the texture panel, select stencil, and select a destination image. Slot creation may take care of some of these steps.
Texture Paint allows the user to paint directly on the surface, flat or not. The paint source is shown below on the left, the human figure with transparent background. The destination image is on the right with UV Map edges. The transparent, of some level, brush stencil is in the middle with the yellow arrow. You may choose the level of transparency. The leg portion was painted. Position was changed. Head portion painted. The pixels were copied from the Stencil image.
The sphere shape has a UV Unwrap which appears in the UV Image Editor window.
Remember to save the destination image. Counterexample. I had to paint twice because I forget to save. Thus image below is different than the one above. Strive to paint on surfaces directly facing view. Avoid painting faces in silhouette. Counter example. The smudge below is when I painted the faces in silhouette.
For the final render in Blender Render the target image was specified as a texture. Cycles also applies textures in a different easy manner. That detail is a separate question.
Know that the slot interface in the texture paint allows you to choose diffuse color slot and create a new blank image for the destination image. I encourage you to try this on examples first which can be discarded then your production work.
Please see this answer as well.