Anyway, back on topic in an attempt to keep this thread from being closed. You should probably just ignore the GregTech argument. As a new player, it doesn't have much of a bearing on you and they're not saying anything that hasn't been said elsewhere already. Enough threads have been closed because of GregTech arguments already.
So, I don't have much to add so I guess I'll summarize and condense a lot of the separate tips people have given. Start out like in vanilla Minecraft. Punch trees, make a pickaxe, mine stone, get stone tools, etc. Once you get the beginning stuff out of the way, start to stock up on metals (especially iron, copper, and tin), and redstone too. Start building machines like people have recommended. Begin with either the Macerator (although if you have GregTech enabled, you probably won't be able to build it yet) or the Pulverizer. Both require different kinds of power. The Macerator uses generators, solar panels, water mills, and a few more advanced power sources. The Pulverizer uses engines. Both will grind each block of ore into two of another item (either X dust or pulverized X). Smelt the result, and you've got twice as much metal as you would have gotten from just smelting the ore itself. Trust me, you're going to need all that extra metal. Definitely start stockpiling. If you run low on space, build barrels (which can hold up to 64 stacks of a single item, right click with item to deposit a stack, left click to pull out a stack) or iron chests (which hold as much as double chests, and can be upgraded into silver/gold/diamond chests when needed).
If you're looking to get into the new carts and rails, build a Coke Oven (place a 3x3x3 cube of coke oven brick, with an empty block in the very center) and put coal in it to start generating creosote oil, which is used for rails, and coal coke, which can be burned just like coal in generators and furnaces and such, but lasts much longer. It's really slow, so definitely start it early, once you have enough sand and clay to build it and enough coal to use it.
Once you've built up lots of metals and redstone and such, you have a lot more options and what you do then is pretty much up to you. You could go to the Nether and start mining glowstone to make some cool stuff, build a quarry to mine for you (make sure you have a way to handle the excessive amounts of dirt/cobble/sand you'll be getting from that), build more power generation and machines, set up automated farms, etc.
If you're going to find videos to watch, definitely look for people who haven't played FTB or the mods it includes before. or people who have but aren't very familiar with it. Yes, they may not always do things the "right" or "best" way, but it's easier to learn along with them than it is to follow what an expert is doing.
And once again, if you have specific questions, don't be afraid to ask. Most of the people here are pretty nice when they aren't arguing about GregTech.