tooltips would help immensely when learning what each thing is in your inventory
Multiplayer spawn protection - presently players are unable to edit blocks near the spawn point. this is a reasonable anti-griefing measure, but should be improved:
Instead of disappearing and reappearing, blocks should be invulnerable.
Upon hitting an invulnerable block, a message should come up, along the lines of "Spawn point protection prevents you from editing this block. Travel X distance to an editable area."
Perhaps visualize this? Could temporarily change the color of the protected blocks or light up the perimeter of the protected region.
beginners' guide
before nightfall, either dig a tunnel or build a wall. enemies can't jump over something 2 blocks high, though you may want 3 blocks high to prevent jumping archers from getting you.
find some coal if you can, to make torches, in order to do anything useful at night