The 450mb is how much you should have available to you. Do you have an sd card installed? Are apps being installed to it?

Try going to settings > application manager > select an app and see where it is stored.

You may want to try moving any media to the sd card as well to free up some space.

I have an LG optimus L70 the phone says it has 1.48GB total storage and 450MB of available storage. How much of the available storage I can actually use? I would like to download a few apps and I don't wanna have my phone tell me Insufficient storage and I delete things try to re-download and it still say insufficient storage. I just wanna make sure I have enough space from the beginning.