I've only just started playing minecraft again after a long break, so my startup routine is limited by the mods I know. When I started my first server after the break, I went for tinkers construct because it was familiar to me and not too complicated to get into. After that I went to thermal expansion and mfr because they hadn't changed dramatically. Enderio wasn't too hard to get familiarized with either, and big reactors was the only power source I needed. Now my startup routine is:
Find a decent area where I can cut into some stone and live in a cave for a while. Punch plenty of wood, in case I can't find coal, and for tools. Usually lock myself in the cave and try to mine some during the first night. Hopefully find some iron and build a refinery (practicalities). Come up sometime during the day and try to find some food and sheep for wool, maybe try to find some clay/sand/gravel for smeltery. Mine some more, build a nice little farm of some sort, gather enough resources for a 3x3 big reactor, start with mekanism machines, usually mine fairly heavily around this point, and expand my farm.