Meach's Mining System
Ill outline it here, so it can help you get rich.
Each mining trip should make you about $3,000 and take about 30 minutes. Not bad money eh? It ONLY works if you stick to the system. I see so many people wandering around randomly, wasting time...
There are just over 3 diamonds per chunk. A chunk is 16 wide, 16 high and 256 blocks deep. Diamonds are found between levels 8 and 16 (use F3 to bring up the co-ordinates, the number next to y: is your depth. The lower the number, the deeper you are. MC "makes" blocks in front of you. So, moving fast in a straight line "makes" diamonds in each chunk as it's loaded. The other mining strategies depend on finding the ores created in the chunk you are in. My strategy relies on MC making ores in front of you.
The perfect mining kit is:
A compass
A diamond EFF V pick (can be fortune or silk, I just use plain and save the better picks. I take two, usually)
A Silk Touch Pick
Food. Beef is best, but anything will do.
Torches. One stack is plenty.
A reasonable sword. Iron is fine, enchanted is better. It kills mobs and cuts spider webs.
Armour. Iron is fine. Its enough to stop the odd random Mobs from wiping you out.
Water Bucket. It sets lava into obsidian. Learn how, or ask. There is a "knack".
I don't take spades, it wastes time changing tools, I just keep the eff V pick going.
There are three main mining methods: Branch, Strip and Straight Shaft. I use the last one, modified. Here's how:
1. Get down to level 11. You will find that most lava on rolyd sits at this level, so you are unlikely to have lava come from above. Also, there is little or no bedrock at this level. Everyone has their favourite level, but 11 is the best for safety and production of diamonds, IMO.
2. No torches, it wastes time. Turn up the brightness in Video Options, you will find you can see well enough to find every thing. The objective is to move FAST, so don't mess about doing anything except mining!
3. Take a silk touch pick. NEVER smash up diamond ores with anything less than a fortune III pick. You get between 1 and 4 diamonds with a fortune, only 1 if you smash the ore with anything else. I use a silk pick because ores take up less space, so I can store them easier.
4. Pick a direction, any direction away from spawn, towns, or people's houses. Use a compass and mine a straight like with a diamond Efficiency V pick. Just two blocks high. Go FAST.
5. Only stop for Iron, coal, gold, redstone and lapis. Redstone and lapis get you xp, anything else of value gets taken too. Sell it at the mall later.
6. You will hit diamonds every 200 blocks or so. Emeralds if you are in the right biomes.
7. When your inventory fills up, turn round and dump gravel and dirt. Keep cobble, sell it at vegans store at the mall. Keep going until you have a good stash of diamonds or your inventory is full. Remember to go /HOME and stash often - getting wiped out with a large stash just ain't funny.
8. Ignore all caves and mines, just keep going straight if you want diamonds. If you want to explore caves, go ahead. You are ten times more likely to get killed in caves than in a straight mine. When you get killed in a cave, I told you so.
9. When you meet lava - DON"T PANIC! It moves slowly. Just back away calmly and use the water bucket to stop it. Move to one side and mine around it, then go back to the same direction.
10. When you come into a cave system, just cross it and use the compass to make sure you mine out in the right direction. If it has lava lakes, use the water bucket to set the lave so you can walk across. Remember to get the water back before you try to cross... It's worth taking a quick look around, but don't hang around - there are plenty of things out there trying to kill you. In a two-block high shaft they can only come one at a time....
If you follow this system, you will make at least $3000 from each trip. Sell off all your other goodies at the mall then use a few diamonds, and your xp, to make new picks. Buy more food and get back down there!
I find that I get about 18- 25 xp from each trip and that an EFF V pick with unbreaking lasts about four or five trips. Make sure you get ALL the coal - its the main source of XP on mining trips, followed by redstone.
Good luck! See you in the mines!