netmeg - 2:19 pm on Feb 16, 2013 (gmt 0)
First of all, welcome to WebmasterWorld.
Second of all - no, don't specify your niche; in fact it's pretty much forbidden by our Terms of Service.
Third of all - read the post pinned to the top of this forum in full - Want to Earn More with AdSense?
Two primary ways of earning more with AdSense include tailoring your site to appeal to buyers at the proper point in their purchasing decision, or just plain attracting so much traffic that your earnings will increase.
At a hundred visits a day, you're probably going to have to try for the first one. Does your hobby involve buying any products or services? It helps if there are advertisers that appeal to your audience.
Do you pretty much know who your audience is? You could try adding more content that would appeal to them, or expanding your topic to cover more hobbies or niches.
You could also look for affiliate offers that would directly relate to your niche - it's not the same 'set it and forget it' that AdSense is, you have to actually sell it, but if done well, it tends to earn more.
Along those lines, you could think about starting a newsletter where you don't have to rely on people remembering to come to you - you send information to them, and while you can't use AdSense for that, there are sometimes opportunities for affiliate offers there.
The thing is, it's not as easy as a book or a website - if it were, then everyone would be successful at it. There's a lot of good information here in this forum if you want to browse through the various topics, and you must have some experience of your own that you can bring to the equation.
The first thing you should do is really think about your users intent when they come to your site. Do they come looking for something to buy, or advice on something to buy, or are they just looking for free information they can consume and then just leave. Do your visitors tend to come back over and over, or do they come once and never return? Are there any changes you can make to your site to keep them coming back, and sharing your site with their friends?