Great first try, but you should try a real vectors design software.
You can take a look on Inkscape, for example; it's legally free and open source, and you'll find a lot of tutorials on internet (and books in libraries too).
The important thing to make printer friendly graphics is to have a decent dpi resolution : about 150, 200 or 300dpi will be good. With a lower resolution, you'll obtain pixelized graphics on the printer.
For logos, etc...same thing : use vector format : PDF, AI, EPS, SVG. So no matter the size of them, you will obtain smooth graphics.
Last thing, for the text : use vector/post script fonts. you can find a lot of fonts for free and legally, make a search on google. You will be able to colorize them, resize, etc...without any quality loss.
for the print, resolution and vector design is the key.
You can also use bitmap graphics (GIMP 2.6 is a wonderfull tool for that, legal free and opensource too) for textures for example (like I did on my 49ers field, or like Weirdwolf does wonderfully) , the only thing is that you'll have to work on scale (real format, high resolution).
Of course, making graphics IS a real profesionnal job, and there is good pro graphists and printers on this forum, but with work and patience you certainly can make the diference on your own
Good luck
EDIT : I forgot one thing, there exists software who allows to make both vectors and bitmap like photoshop creative suite, for example, but they are quite expensive.
another thing, screen color is not always the same in print. SOme RGB colors are not printable, so the printer will extrapolate and maybe create glitches or saturations. But now with modern printers and digital tracers, it stills a minor problem (except for pro print graphists of course).
To conclude, there is no ONE good technic and other bads technics, you can obtain good results following diferent paths. the only key thing is (IMHO) the resolution and to work directly on scale (example : if you use a logo, even in bitmap, BUT use it at the good size and resolution, to avoid pixel effect).
hope it helps
