ok... i need some help... i went to my first trip to the nether and is insane... I spawn in a big dark room full on soulsand (slow movement)... almost a minute after spawn a big thing spawn and try to kill me... wall myself and kill it.. light part of the room and try to get some redstone... just mine 3 pieces a hear a ignite sound... turn around to kill the "creeper" just to see the explosion in my face of the REDSTONE... I mean, wasn't gas or anything like it... i say fine.. let me get some nether quarks... mine just ONE and it explode... How can I mine something if everything i try just explode... and lets just don't talk about the mobs that come after that... run scare to the room with the portal to find a fucking creepy spider and some dude that take all the torches and shoot me... after that I give up... came back to the overworld... break the portal and cry in my new presser (the only good thing that came from that)
You pretty much just have to be ready for the nether, fully decked out in armor and all that good stuff. ALL nether ores have a percentage chance to explode, the best you can do it mine what you can out of a vein, and the moment you hear the hiss look quickly to see if you can see smoke coming off one of the ores. That is the one that will explode. If you can break it fast enough it will stop. If you don't think you can stop it within 3 seconds, get away from it quickly. That's just how you have to play in the nether. Besides with full Damascus Steel armor (Best non enchanted armor you can get really pre-nether easily), the explosion won't even break through your armor absorption and hurt you even at point blank range. Fire might possibly bring you down but yeah, you just have to be cautious in the nether, and do not go too far from your portal unless you are comfortable with it. It is easier to make mineshafts in the nether than to hunt out in the open (less mobs to deal with in general)
So that's the best advice I can give you. The modpack is supposed to be super hard, that's the whole point really.