Quick & Simple Tip:
I was chatting to a group of travel bloggers last week and a lot of them found this tip useful.
1) If not already, start analysing your site. Google analytics is very useful and free.
2) Find out your most popular pages from organic search. You might be surprised which ones they are, could be in some unloved corner of your site!.
3) Make sure these pages are either monetised, lead into other well monetised pages or have some other benefit for you such as encouraging your users to subscribe to your email or RSS feed.