I have ubuntu on my computer because I couldn't afford windows, but I do not know much about programming, I mostly use it for Uni, so, with google docs and OpenOffice I manage to supply my needs; however, I frequently found myself in need of some special characters, such as: α, β, γ, Δ, ≥, ≤ and µ.

What I do is: google it, and copy-paste it on the document; is there a way to add the combination on my keyboard, for example, if I press alt+B = β

I mean, it isn't necessary, but It would make my life easier.