All of the above are ways to make money with a blog.
Remember that a blog is just a website that is structured for easy content management (i.e. posts).
Even though what has been said is correct, there are reasons to stay away from a few of the suggestions.
PPC (Pay-Per-Click) can get really expensive is you do not know what you are doing. The general consensus is that, unless you have a decent budget to start with, it is best to stay away from PPC - at least at first.
Adsense is also not such a great idea (in my opinion) as it needs to be set up properly so as not to detract from the content. Not so easy to do.
But, you did ask how to make money, and the very best thing that you can do is to scour your brain and decide what you know about and like ("And Like" is really important).
Develop your blog around that topic (posts and such), and create your own product; one product to give away, and another to sell. Your giveaway product only needs to be a few pages, but what if you were to give your subscriber (get to that in a minute) 20 pages of really good information on your subject? Your first impression will be much more lasting, and your credibility will go through the roof! As far as the paid product that you create, relate it to the giveaway topic, but don't make it the same.
Okay. Several people have already mentioned
the "All Powerful" auto-responder. The auto-responder is crucial to making money online (the way you see it supposedly being done by others).
I have gone on a bit long here so I will try to "Nutshell" the rest.
Your auto-responder collects email addresses, and sends back a message to your subscriber. You send out more great content to your subscribers (kind of like posts, but specific to your niche), and build up trust with those who are on your list.
To get people on the list you use a squeeze page (I know you know what that is) with the super-duper headline and all that. But, you also put in your sign up form that you created from within your auto-responder service.
Oh, I almost forgot, that trust that I was talking about building with your list, you do that with a follow-up series of emails that you need to write. Many marketers will tell you that a week of follow-ups is good enough.
I think that it should be at least 3 weeks. Just me.
That squeeze page (mentioned above) will have the "Plug" for your giveaway product. Then somewhere in your email follow-ups (5th through 7th), send them to a sales page for your paid product. Some might buy, or no one will.
So, at email 10-12, you send them back to your sales page.
And so on. These are certainly not set in stone, and will be varied depending on the niche, and product.
Seems like a lot of work? YEP! It is at first, but once things get rolling it is not as time intensive. Plus, once you get catch on to what you are doing, you will be able to get more done in less time.
Long-winded here, didn't do such a good job with the nutshell thing, but hope the comment helps.