Trying all kinds of mods can add interesting things to your game play. I would start with small addons and try those and then go to HUGE mods last.
Some good online servers would be RAW, they are pretty nice and Colours is a nice server, but has their own Mod. You can Download it Here
now since you are talking about mods, I am sure you understand that you'll need FLMM.
I am also working on my own project, which should come out later this month.
Well those are two servers I know are very nice for new people who don't want any problems with the bigger players there. Very nice people there. Just ask around.
FYI Raw server doesn't have a mod, so don't use any.

Hopes this helps get you started,

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