hey fellas , when I have a few split windows and I do c-W o to focus on a particular window , is there a way to go back to the previous split setup

AFAIK there is no native method to do that. You can do :tabnew % to focus on a particular window in a new tab and do <C-w>q to go back. You can map it: nnoremap <C-w>z :tabnew %<CR> (`z` as “zoom”)

You can use C-w | and C-w _ to maximise a window vertically and horizontally respectively. Useful if you use only one type of split. C-w = can then be used to rebalance the windows.