gr.group theory – Irreducible representations of finite p-groups

Let $G$ be a finite $p$-group. What are irreducible representations of $G$ over a field of characteristic $q$, such that $(p,q)=1$ ? Can we say something in general ? In particular, if there exists some technique to find those explicit representations in case of small groups of order $p^3, p^4, p^5 …$ ?