Monster is a good start as it has basically everything you could possibly want.
In terms of mods:
- Thermal expansion is the goto mod for newer players as it's incredibly simple to work with and the power system is used by many other mods.
- Buildcraft is also good for this (before more awesome mass mining apparatuseses existed, the quarry was THE thing).
- Tinkers Construct. Great crafting system for tools and weapons, much better than vanilla, it's an integral part of my early game setup in virtually every world.
- Thaumcraft. It's magic
It has a lot of content and some of the concepts are a bit weird to get your head round at first but once you work it out, you'll make extensive use of it because it's win.
- Applied Energistics. Basically it's an entire system for storing all your stuff in a fraction of the space a normal inventory system would use, using it to automatically craft things on demand, process ores automatically (in conjunction with other mods' machines), it's an all-encompassing automation tool that I personally can't survive without. PRAISES BE TO COLIN!
And ignore people who tell you rotarycraft is difficult. It just requires a slightly different approach than traditional mods. And the rewards you get once you work it out are fantastic.
Other stuff:
For renewable resources of all kinds (all your minerals, mob drops, anything you can think of really), look into bee breeding (from a mod called Forestry, but there's an uber way of doing it now called Gendustry) and/or Magical crops (which is so awesome some neckbeardy people complain that it's cheating
)
For automating pretty much any crappy task you don't want to spend hours doing (harvesting your farms, enchanting, brewing potions, killing mobs etc etc) there's Minefactory Reloaded (MFR).
There's also several mods which add a ton of extra little devices that do all sorts of incredibly useful little tasks, while the mods themselves have no overall theme. Randomthings, Openblocks and Extra Utilities. I find myself adding tons of their little doohickeys to my bases because they are just so handy.
Also blood magic. It's disabled by default in Monster, but you can enable it at the touch of a button, and it's FANTASTIC if you like to extract living essence from
gelflings mobs/yourself to power various awesome contraptions.
That should be enough to get you started, for everything else there's
mastercard exploration