Evolutions are a big part of Khazix and how you play him. The Recommended evolution path that I always do is R > E > Q. This allows for a third duskblade proc at level 6, Dive and escape potential At level 11, Finally Dueling and objective clears with level 16.

Pros:
Massive Damage
Dueling potential
Gapclosers/Escape

Cons:
Weak Lategame
Long CD
Very Punishable

So for Jungling, the path I go is (If blue team) Red buff > Wolves > Blue Buff > Scuttle > Gank/Gromp. (If red team) Blue Buff > Wolves > Red Buff > Scuttle > Gank/Raptors.

If you are against champions that counter you, try to stay in your jungle and play more passive. Getting caught out an early game is the worst thing you can do. Always go for early pickings and get an early carry

If you are against champions you counter, try to counter jungle as much as possible. Make sure that they are completely out of the game and make it a 4v5.

When you run into a fight, do not let them poke you at all. Initiate the battle by going W > E > Q > R, you want to ult immediately after landing so they do not have you targeted and if done right, you should have taken no damage. While in ult try to avoid any aoe attacks the enemy might use, Go up behind them and Auto > Q > W > R. Now is the time you have to decide... If you think you can kill them repeat the 2nd combo and if not, use your last ult to escape.

Tips for escaping.
When Running from someone you can kill in a q simply E > Q > E. It is ESSENTIAL that you e first and q midair for maximum distance away from whoever else may be following.

When running from someone you cant kill, try to move in unpredictable ways, If you have ult try to activate it and run the opposite direction they saw you going in. In the case you do not have your ult ready then try to e over a wall and run for your life.