You are looking for a tribal dog tattoo - which is awesome. Ideally your choice reflects your personal tastes and sense of aesthetics. But now comes the most important part: searching for the perfect image. The time and effort you put in finding the right tattoo will reflect in how much you (and others) love your tattoo, and for how long. So definitely do the hard work, it will be worth it. For my part, I hope I can help with some tips.
First, avoid using Google as your source for images. Google's image search is great for most things, but it doesn't cater to tattoos in specific. More importantly, it is not unique - everyone has access to the same images and options. If you get a tattoo, you want to know that you are the only person who has it - it should be part of who you are.
My suggestion is to try a site that caters specifically to tattoos. The best feature of such sites is that they offer images and resources that are unique and available only to members. For a fee, you can choose images and work personally with a tattoo artist to customize them, so that your tattoo really reflects and satisfies your own unique tastes. On such sites you also find communities of other tattoo lovers, people who have a wealth of enthusiasm and information to share, and can answer your questions, especially if you're a first-timer. On the best sites you will also find reviews of tattoo parlors in your area, which can be a great help when trying to find a place that is highly regarded, reasonably priced, and safe.