Well frist, you want to make sure you've played the story line and had some fun without any mods, on SP and Online. Then you want to have fun with some mods.
Then a very basic mod that would be prefect to slip in would be
CHSP Mod. It's a online only mod and the server is german but I've played on there for about two years now and it's always been peaceful.
If you are interested in heavy modded online FL, I would check out
Monkey Universe,
Crossfire,
Void Mod,
Colours Elite Mod, and
Tekagis Mod.
Those are some nice online FL mods.
Now SP mods that you could play by yourself would be
Deathwish Addon,
Get all Ships Mod,
Open SP Mod, and
BlackMesa Complex Tech. Mod. Those are some mods that would be nice forplaying offline. The OpenSP would be used with other mods so you don't go through the story, It just skips and you can do what you want without the level limit.
So that should get you started on mods for awhile, have fun.
QuEsTiOn AsKeR
Last Hope MOD
Last Hope Forums