Weapon modding is a good place to start as it’s fairly well isolated from system building which can be quite complex. You can PM me with any questions on most aspects of modding except ship building and texturing never did get round yo them LOL
Get a good text editor for the ini files I use Notepad ++, for system work FL mod studio is my choice
https://code.google.com/p/freelancermodstudio/downloads/list?can=3
another essential tool (primarily for info cards) id FL Dev
http://forge.the-starport.net/projects/fldev/files
If your mod is intended to be quite large you need to have a custom dll to contain the info card data, I assume you’re using the TCM starter pack? it contains several custom dlls set up for you.
http://www.moddb.com/mods/the-underverse/downloads/freelancer-total-conversion-mod-starter-pack-30