I don't have any real tips or clues for you, but let me describe my own situation. Maybe this is somewhat insightful.
Until about 10 years ago, I wrote most things in either POSIX shell (actually the subset of POSIX shell supported by FreeBSD's /bin/sh) or in C. And then I decided to make myself more familiar with Python – and that changed everything. I already knew Python before (as I knew Perl, Ruby, Java and others), but hadn't done anything serious with it. But then I discovered it is actually the perfect language, at least for myself.
Python is dynamically and strongly typed. Because of its type system, friendly syntax, functional features (like list comprehensions) and extensive standard library, it is well suited for rapid prototyping. You get results very fast, much faster than when using C. Interfacing with C code is so simple, it's almost ridiculous – both embedding Python in a C program and calling C code from a Python program. For example, I have written a video processor framework in Python that handles 1080p MPEG4 video in realtime; only the core frame functions are written in C (this is like 2 % of the code). The first working version of the whole thing took me one weekend to write.
As of today, I write simple things in /bin/sh. Almost everything else I write in Python, and if there are any parts that are performance-critical, I write just those in C.