Green and blue screen fail

After researching online techniques to create a colour splash of red in a clip with black and white, like in Sin City, I found I could do it using iMovie and Final Cut. In school, we have iMovie downloaded on all computers within the class but Final Cut is only on one at the minute. Although it should be installed on more computers soon, I know I shouldn't rely on someone else (like the technician) because it may end up that there is a problem. 

So, after researching online, I found I can create the effect on iMovie, but difficultly. The parts I want to be shown red, I must have as actually green or blue, so I can use the green/blue screen tool to change it's colour. For me, this is hard because I don't know where to get green or blue lipstick or something that will look like blood. I can improvise, with food colouring in some way, I'm unsure how I'll do this yet but if I need to use iMovie then I will find a way. For me, it's easier to film the parts I want in red, in red, using the red lipstick and fake blood props I already have, to create the clip. On Final Cut I can use the red lipstick and fake blood, and just use editing software to change the rest black and white, without going to the trouble of finding different props.

While in a lesson, I recorded a clip of blue and green pens, so I could edit the clip using both blue and green screen to see which one was better. Below is a screen shot and video of me using blue screen, as you can see, the blue pen looks red due to the red over or under lay. So it does work, but the green screen didn't. This causes problems as I'm unsure which colour will work for my clip, so I may need to buy/create both blue and green lipstick and "blood".

The video seems like it won't load, but it says it's loading, so you may have to wait a while.

Another problem, as you can see in the video, is the red colour is messy due to the quality of the camera and the other blue tones in the video. I did end up adjusting the saturation, contrast and red green and blue tones to make it look better, but for me it still looks unprofessional. 

After trying this editing technique, I really feel against it. I think if I try and use the blue or green screen, it will either not work for my final clip or look like an amateur scene, which of course I don't want. 

Hopefully I'll be able to use Final Cut by the time I need to film/edit my footage.