Three free WordPress plugins have really helped me.
Cache Enabler – I have a Computer Science degree and couldn’t get W3 Total Cache working on my web space. Cache Enabler is dead simple and works like a charm. I have web space where WordPress is natively slow so this saved my butt.
If you need to test the speed of your page, Google Pagespeed Insights can help.
Duplicator– Most plugins to move WordPress sites are expensive. This one will move large sites for free. Say you want to pull down a copy of a remote site for your local server. Simply run it and download the files and then run the install in your local web space and it will give you an exact copy.
The SEO Framework – Covers all the bases of SEO including specific tags for social media. The paid version of Yoast might be more robust but for most people SEO Framework should be enough.