The first is to make sure you put your targeted keyword in your title tag. Some people neglect this, thinking it's pointless but it does indeed help. Some say it helps significantly so there's no harm at all in helping Google identify your site and help them take notice of what your site is about.
The second is content although this could also be placed first in the list! I put an exclamation mark there because this is one of THE most important elements in order to get your site up in the rankings. Google places incredible emphasis on unique, original and high quality content. Using PLR is fine as long as you change up the wording but you certainly don't want to simply copy and paste existing text from elsewhere.
The third is videos. Ever since Google bought YouTube, they put a great deal of money into elevating the viewing experience. Google puts millions of dollars into Youtube, playing around with the interface, trying to increase quality (remember the old days of 360p videos?) amongst other things. Videos helps your ranking a great deal but you also need to make sure you optimize the content of your videos including title, metadata, and targeted keywords.
The fourth is the proper use of bold, headings and keyword density. You don't want to stuff your copy with tons of keywords as it will do more harm than good for your rankings. You need to use the H1, H2, H3, etc efficiently and Google will take care of the rest.
The fifth is social media. This is the one area where there are no limits. Push your site all over the social media space including Facebook, Google+, Twitter, Pinterest and wherever else. Integrating social media into your site (facebook buttons, etc) only helps and it helps considerably.
These are only some of the factors that can help increase your rankings. There will be more obviously. If you have any other things that you've seen help website visibility, feel free to post about it here.