[LCP]Pre-planning/documenting software projects

[juman]

I am one of those techheads who now and then code little utilities that
help me with specific tasks. Programming is something I have learnt
mostly by myself and prefer coding in C but sometimes I also do
shellscripts, PHP, Perl and C++.
    Now I am trying a little bigger project which also includes more
pre-planning before I actually sit down and start coding. So I started
to read up on some diffrent tecqhniques for software development
planning. And as I can see it the biggest one is using UML and some
graphical tool to produce it. But I do most of my work in a Linux shell
and wonder what tools and techniques there might be not using Windoze or
X?
    I am also looking for online texts about software development
planning or books that you might recommend. Most of the text I have
found so far is more about how to plan your resources then breaking down
the actual software idea into modules so that you can begin coding.

/juman