You can also offer private ad spaces on your site or blog. You can place them in the sidebar or within your content. You can put together a page on your site “advertise with us” for example and explain the process and how to contact you if they are interested in advertising.
An advertiser will want to know how many visitors you have + other website data, so make sure you haveGoogle Analytic or another tracking program installed.
You can also reach out to companies that would benefit from your traffic and see if they are interested to place an ad with you.
It is very hard to recommend a set price there are too many variables to put into consideration, traffic, conversions, niche and more. You can always check out other websites in your niche and see what they offer.
Helpful tool to use. I use a tool called OIO publisher that will help with payment and stats.