the best place to start is to just do research. find out the average costs of a sw vs a fw tank (fw is cheaper to start......). look at fish, find some you really like, then research them to find out tank sizes, compatible tankmates, substrate requirements, and water requirements. find out if the fish you like are easy or too difficult for a beginner. i literally went to my local fish stores and just walked up down the isles of tanks and wrote down names of fish i liked. then i did my research. i priced tanks and found out what sizes of filters and heater and what not i'd need, then priced some more.
since youre a newbie, freshwater is probably the best route to go. livebearers (mollies, guppies, platies,swordtails) are quite easy to care for, so are most tetra varieties.
i know youre looking for more specific info, but really, your possiblities are endless if you have timeand money, you just need to figure out a few things yourself first.
things to keep in mind, the bigger the tank, the easier it is to keep the water conditions stable.