i was just wondering how to add model blueprints into blender properly. i know how to add them but not how to make them fit to scale. The only time i have used blueprints they were in 4 seperate jpegs and i didn't really need to crop and scale anything. Here is the pic i am using:

Just scale it by eye, using the height as an indicator (that's what I usually do).

i probably could do that but is there anything more specific??and also is there any way to move the pic or is it set in the centre??

You probably didn't know that it's called rotoscoping:
http://www.google.com/search?source=ig& ... f&oq=&aqi=

i mainly meant to ask how to setup the right scale for each image and things like that.....

What I gave you should let you put the picture in the background. Instead of a solid color that you're modeling against, you have a picture that you can put your model on top of to check the scale.

i already know how to add Background images in blender and i know that they're transparent. i just am not sure about getting the ratio right between the different pics.
eg my reference pics might be right in xy view but in zx they are totally off and are the wrong size. is the only way to fix this educated guesses or can i actually calculate the size i'll need to make the pics?

I think I see what you're saying. The front view is about 73% the size of the side view with a 2% margin of error (compare the similar circles in the picture). You will need to edit the picture in an image editor to make the appropriate corrections.

Or you could setup what is commonly known as Image Planes.

Create a Plane Mesh (One Sided Square polygon) and then apply the reference image as a texture (make sure you give each plane a new material that is not the default scene material) using a Planar UV, make one plane for each reference image. Then scale and rotate the planes as needed.

Example(pulled from a quick google search)

thanks for your help guys!! That plane idea sounds pretty good except for the fact that for some reason textures don't show up unless i render the image...........
EDIT: i know i should go to texture view not solid but it doesn't seem to make much difference..