How to avoid update without damage security

Hello,

I know that to avoid any security breach we have to update all the software we have.
But since the memory in a cell phone is not big how can I avoid update without damaging security for my android.
I went through many resourses Mobile Security Video for help but,did not find any help.
Please help me out.

Any help will be appreciated.
Thank you .

nowadays internal memory should suffice, it will replace all other updates installed previously if om not wrong.