Drawing and making templates are my hobbies, so recently I became interested in graphic design portfolio which is a kind of combination of both hobbies. What would you advice if you have any experience?
I have many ideas for design and I would like to know some general things about building a portfolio. Could I be able to use more than one colour, if I have simplest mediums?
I'd probably suggest checking out Smashing or Behance they're probably going to give you the best rounded holistic experience with design as process and resources.
Otherswise http://net.tutsplus.com is also rather good for finding the specifics for how to do something with a tool to produce a certain look, though many creative and design types tend to think "tooling" for sites like that.
You can try to further enhance your drawing and template making skills. As you collate more designs that you can showcase as your portfolio. Take in design projects from relatives and friends and from there you can build your portfolio.