I collected obsidian with my new (At that time) diamond pick, constructed a portal, lit it, and entered the nether...
Only to find that my portal was on a peninsula, AT lava level, surrounded by a well hundred blocks on each side by oceans of lava that had plenty of space for ghasts to spawn. And if you're wondering why I said "Peninsula", its because it is connected to land -- or should I say, the side of a cliff. I tried exploring it once, with my backup iron tools, and got lost very quickly and later fell down two ravines I didn't see and got burned by magma blocks on the second one. The nearest land besides that is hundreds of blocks away and there's no good method for me to bridge there without getting knocked off by ghasts every few blocks. I need to find a nether fortress or I have zero hope of finishing the game or beating any bosses. Should I somehow tower to the nether roof and start building a highway there? I don't know what to do -- any advice would be greatly appreciated by me, thanks.
If you don't like your chances going up and over the cliff you could try tunneling through it.
If you do want to pillar up to the roof you can do so in relative safety by building a plus sign shaped tower and keeping the sides taller than the center, when you get within reach of the ceiling I'd suggest building a large enough platform that you have somewhere to go if you dig into lava, also leave a quick and easy way for any lava to flow over the edge away from you. When you want to go back down just dig down through the center and place ladders.
The Meaning of Life, the Universe, and Everything.
Somewhere I think...
You can also make another portal in the overworld. Just remember, if you have to travel hundred if blocks in the nether to get to more land, you have to travel 8 times that much in the overworld. If you dont know what fast traveling in the nether, just search it up on youtube or something.
If you are on a shelf at lava level, you are best off going up that cliff, getting to a higher ground. Build a tube out of cobble with ladder inside, hugging face of the cliff. You will likely emerge on a higher plateau, from where you can explore easier. At this time, it might be a good idea to break your existing portal and rebuild it at a more convenient location. I generally find most traversable landmass in the nether is in the Y=60-80 range.
Building a tube out to the ceiling is also an option. But once there, I would rather suggest building a horizontal tube just under the ceiling. You can build sides against the ceiling, and then build out the floor, without exposing yourself much. I do not advise digging in the ceiling itself cause while safe, it really gives you no idea where you are. Tunneling at Y=120 is good when building the fast transport network and already knowing the coordinates.where you want your portals. Not when you are still exploring/looking for fortress.
You can also build shaft/ bridge using pistons without exposing yourself to ghast fire. A piston pushing blocks will 'squeeze out' any lava. So if piston will not extend when activated, it means it got 12 solid blocks in front of it. This technique can even be used to punch your way through a lava ocean in the event your portal generated in a cave under lava.
If you are not averse to cheesing it a bit, you can start a creative world with same seed, and then just fly around the nether a bit to see where things are.
If you post your world seed, and your portal coords, some here can offer a bit of more specific advice.