Your temps are looking good but you didn't describe what powersupply you currently have. It could change your result slighty or greatly...
There is no blueprint for any overclock. The way to accomplish this is by increasing by very small increments and fully test the rig for stability at each step. Start by increasing the gpu core clock 25mhz, test, then 5mhz increments all the way to the maximum it is capable of. Stability testing is the key here to finding the maximum clock. When you reach the maximum, backup by a few increments and that will be the max 24/7 overclock.
You then put back gpu core clock to it's default, and you start incrementing ram the same way as you did for the gpu. Again test a lot, and when you find the max clock, backup a little so you won't wear your card in the long run.
Oh and always check it's temperature. When overclocking it is recommended to put the graphic card's fan at maximum speed since the card will get hotter than usual.