Never keep lava buckets in your hand; the chances are you'll use it by accident and die.
Spider eyes will fill you to more than 90% hunger but they will hurt you in the progress.
Never use gold for any sort of tool, the durability is terrible and it takes a while to mine anything.
Leave it to the Big Tools
Only mine valuable resources with a good pickaxe or else you risk destroying the block.
It takes 10 minutes and 40 seconds for you to smelt any 64 stack of something in a furnace.
Sneak and Reach
If you sneak or crouch you won't be able to reach as far.
Use cactus instead of lava to destroy unwanted items, its safer and more efficient.
Using a tool for something besides it's purpose will make it lose its durability twice as fast.
Easy Does It
Hold down shift while walking and building on any cliff faces or ledges so you don't fall off accidentally.