I can only speak from my experience...

Some granite fabricators have showrooms. I suggest you go there to give some basic idea with what you want. Then, narrow down to your choice of color and desired thickness (2cm=3/4" and 3cm=1-1/8" although some are 1-1/4").

Next, using google search and type in Granite. Go to these websites and go to your color choice and look up some of these granites and their names. Remember, shades and design may varies some, that's why at the end you'd still need to go to a granite yard to chose the slabs.

Next, educate yourself about granite by research on this website. Some experts had given lots of information on granite. One such wonderful and thoughtful person is Stonegirl. Do a search on her and you'd find tons of information about granite. Not all granite are the same; so, you'd want to know which has low maintenance and which has high maintenance.

Visit some of the granite yards in your area. Although, most don't deal (selling) with you directly, they do welcome you. After all, you're the one that will make the final decision of which granite to purchase. Most fabricators have their favorite granite vendors but would still do business with your choice of granite seller (yard).

It took me almost 3 months visiting different granite yards in town before finding the one I like and that would fit my budget.

Some tips:
1. Always bring a camera with you and take as many photos as you can. They will help you to make choices afterwards.
2. Bring a backsplash tile and/or a cabinet door, or whatever to help you see how well it goes with the granite.
3. Bring a sample of the granite home if you can for testing. Sometimes, you can't and that's when the photos are good to have.
4. Ask as many questions as you can with the granite yard salesperson.
5. Avoid having any granite fabricator coming along with you until you made a final decision. They may steer you to chose something that you may not like. But, they're helpful to help you chosing a good quality slab once you made your choice of which granite to go with.
6. For quality, avoid if possible granite from China (all) and India (most but not all). Stick with Italian and Brazilian if you can.

Remember, stick with your color and granite thickness to avoid getting overwhelmed with choices.

Good Luck and mostly, have lots of fun!