How to improve load speed and First Byte

After running my joomla site through the webpage test. my results are as follows:

I would be grateful for any advice that can help improve the the page load and also best way to fix some of the ‘errors’ listed in the test results.

thanks in advance,

There are few thing you can do and these can improve significantly.
[]Fix the 404 errors
]Combine the css files, js files. There must be a joomla module or setting which can do this for you.
[]THere are too many images combine few to reduce http requests
]Install APC on server and use somo joomla module for cache. TTFB depends on server configurations, so make sure your there are no slow queries, and there is enough ram available on server.a