i dug so far down that there was just blue space and i fell in it by accident and died and of course i had full inventory again and that was completely lost.
When digging down and hitting bedrock, keep track of how many levels into the bedrock you are. I believe bedrock is the bottom 4 levels (is it 5?), so don't dig under your feet if you're in the last level or two of bedrock in case there is an opening into the void.
I guess there is no way to reset your spawn point in SP? my spawn point was off on some small island with nothing near it so i had to travel a bit to find a decent place. now my compass points to that island and if i die i spawn there.
Unfortunately, no. You may want to build a chest at your spawn point and drop a few basic materials (maybe some stone tools, torches, and a sword) so you're not completely empty handed if you die.
When you are exploring, only take what you absolutely need with you (sword, torches, tools). Leave everything else in an easily findable chest. If you get some nice loot, immediately head back to a chest (or even create one there and drop stuff into it) so you don't lose valuable stuff if you die and can't get back to your corpse in time.
also, what am i doing wrong? I rarely find ores and stuff, even digging down to bedrock. just a few blocks here and there. i read that you find diamonds near lava and have found maybe 6 blocks total. i dig all around the lava and never find any more.
For each kind of ore (including coal), there are two "altitude" limits. The higher of the two is a hard limit -- you won't find *any* ore above that height (with the last layer of bedrock defined as 1, and sea level is 64. The lower of those two limits is where that ore is more frequently spawned. I don't remember those limits off the top of my head, but basically you cannot find anything other than coal above sea level, and diamond is something like 16/12 (i.e. non-existant above 16, rare between 13-16, and uncommon between 1-12).
Note that the frequency of any given ore is constant after you go below that second "level" for that ore. For example, if coal's numbers were 128 and 64, anything below sea level will have an equal chance of finding coal -- the frequency doesn't go up or down the deeper you go.
Also to take into consideration are the fact that ores are found in "veins." Coal veins can be large, often being 4-8 blocks wide in 2 dimensions and 2-4 blocks wide in the other dimension. Note that not all blocks in the vein will be the ore, but it will be substantially ore in that vein. Therefore, if you find a particular ore, make sure you dig around it to make sure you get any neighboring ore.
I believe that iron is a maximum of 4x3x2 and all others are 3x2x2.
My strategy for finding ore is to dig down to bedrock, go up about 4 blocks, and then dig straight caverns (1 wide by 2 high) for a while until I run into lava or get really far away.
