I am trying to write code for a diagram I have in tikz. I am very new to tikz so this may be an easy question but here goes. I have some code like the following:
\begin{tikzpicture}[scale=.95]
\draw [<->, thick] (0,0) coordinate (a_1) -- (2,1.8) coordinate (a_2)node[right]{$\mathcal{M}$};
\draw [<->, thick, color=black!40!blue] (1,0) coordinate (b_1) node[right]{$\mathcal{N}$}-- (1,2) coordinate (b_2);
\coordinate (c) at (intersection of a_1--a_2 and b_1--b_2);
\fill (c) circle (2pt) node[right]{$X$};
\end{tikzpicture}
But the issue I am having is that in more complicated diagrams, the text labels are in too large of font and intersects with lines. How can I make the font in the label nodes smaller?

\tikzstyleis obsolete. Please use\tikzsetand the/.append stylekey instead. – Tobi Sep 05 '13 at 20:38