Your biggest problem is that you don't have bike fitness and don't really know what you'll be doing with the bike. Sadly, none of these will come until you've spent some time on the bike. This means that the first bike must be regarded as temporary (even if you do wind up riding it until you wear out from old age - that happens too). That suggests buying cheap but believe me, if you buy a cheap, horrid bike, you won't ride it. My story with going this route is described on my website
here in my story about the
Sow's Ear.
My advice is to do a loooooot of shopping. Go to as many shops, far and near, as physically possible (and a few where it's not). Ride as many bikes as you can, sit on as many as you can. Yes, you will get confused, very confused and distressingly quickly, but after awhile, your bulldust detector tunes in and you start to pick the good advice from the rubbish. You will also find yourself walking into a shop and going to a particular type of bike - that's when you start to get an idea of what your heat wants though it's not a precise tool - I always head straight to the top end racing bikes though I have no desire to own one, I just love them. But you'll find that after awhile, you will be pulled to a style of bike and that's when serious test riding pays off.
Two things are critical in buying a new bike - buy the bike you fall in love with, seriously. A rationalised decision will always be the wrong one unless you find that love later. The other is the fit of the bike - fit is more important than anything else, and that's the message in my
Sow's Ear story - the bike was too small and it effectively kept me off the bikes for a couple of years (and about 10kg of added ballast).
How do you find a good bike shop? By visiting a lot. The shop for you is the one that listens to YOU and your individual desires and needs. It's the shop that understands you for the cyclist you are, not a customer with a wallet. It's the shop that will go straight to their catalogues if they don't have what you need on the floor.
Have fun. Buying a new bike is confusing and hard work, but by cripes it's fun
Richard