I only have 4 tips for you finding diamonds... sorry about that..
My tips work for me, but I don't know if it works for you xD
I did not copy this tips from anywhere, I made it,
Okay, while following my tips, i found a total number of 56 diamonds. Here it goes!
Things needed: 4-5 Iron Pickaxes, A Bucket of Water (Incase if you fall into lava), Full Stack of torches, Flint and steel (For Bombing xD) and Tnts!
We all know that Diamonds can be found on layer 16 and below.
1) You can mostly find diamonds near lava.
2) Make sure you mine a big shaft/tunnel
3) And the most greatest tip (for me) is that Diamonds can be found among other ores! So make sure you mine above, under left and right the ores
4) If this tip doesn't work, then try BLOWING UP!! the place with tnts. But make sure you place the tnt in the correct place. Trust your instinct (Not so good tip )
I Hope you like my tips!
If it works, you might wanna give me a green plus right in the bottom right corner
Tips from other fellow people (Give them a green plus if it works)
One layer above lava so you're safe!
The best tip for finding diamonds is, dum dum dum duuum! Branch Mining.
I've only made one serious branch mine so far, but I found... I think it was about 15 diamonds fairly quickly. I also found a ton of redstone, iron, coal, gold and lapis. What it does is that instead of making a big hole to find ore, you make tunnels quite close to eachother to eliminate almost every possibility that ore will not be visible in at least one tunnel. Works like a charm, it's structured and it looks good.
in about 5 minutes of branch mining i got 4 diamond!! =DD