How to get into Fish-Keeping?
First, do your research. Look up some examples of aquariums. Find what size tank you want to get and what you want to do with it. Generally the bigger tanks are easier for the beginner since there is more water volume to dilute harmful compounds like ammonia. Next, find and research the fish species you want to get. Make sure they are compatible with each other and the size of tank you will be getting.
Now that you have a list of items/livestock you will need to go buy them. A good store for supplies/tanks is Denny's Petworld in Kirkland. The best store for livestock is Aquarium Co-op in Edmonds. Both stores have staff that are knowledgable and open to helping beginners in the hobby. Don't be afraid to ask them any questions you have. If you feel confident in your equipment choices amazon is a good choice due to reduced prices and fast shipping.