Make sure that you're always posting amazing content. The better your content and the more interesting your blog, the more people will link to it. There is nothing better than getting free links just because people liked what you have to say! Keep your mind on the SEO side of things, but also remember that you are ultimately catering to the needs of the people in your niche. If they like you, the search engines will like you.
For example, if your hobby is cooking, start with the different categories of recipes you enjoy cooking: Baking, Grilling, Vegetarian, Gluten Free, Beef, Chicken, Crockpot, Budget, Exotic, etc. Then break it down from there: Baking: Cookies, Pies, Cakes, Breads, Quick Breads, Baking Tips, etc. If you’re not coming up with enough categories, sub-categories, and topic ideas, it’s probably not a sustainable topic for you.
Working with advertising networks isn’t your only option when it comes to selling ads. If you end up with enough traffic, advertisers may come directly to you and ask you to place their ad on your site. You can also contact advertisers yourself. The biggest difference from the above mentioned option is that there is no middle man, which means you can set your own ad rates.