OP do keep in mind that hotels are in business to make money and if it were common to get great room upgrades just by asking, they'd never sell any "fancy" rooms, which would reduce the amount of money they'd make.
Having elite/frequent guest status increases your chances of getting a treat in the form of a free upgrade but in the industry that's seen as a way to thank the guest for their business in hopes of generating more loyalty and revenue. If you've not demonstrated that you spend money at the hotel (or at least the brand), it's not really likely that they'll give you something better than what you paid for, just because you asked. After all, you'd not expect a restaurant to give you the $40 bottle of wine when you order the $20 bottle and ask nicely for the better vintage, unless you were a very frequent customer (and even then I wouldn't expect it.)
Which does not mean don't ask, but set your expectations accordingly. If it's a special occasion (honeymoon, anniversary, etc) and having a nicer room is key to your enjoyment, then book the nicer room and don't be disappointed. While the advice to email the hotel before your arrival is well-meaning, I find it sometimes more harmful than good, as it sets the general public's expectation that they can have that honeymoon suite just by asking, leading to some very disappointed guests when they are told No.
The advice about Virtuoso and Nor1 is good; read up on those. Amex Platinum can often give an upgrade benefit when booking your hotel through their travel site, as can some other credit card companies. But the $20 trick really only works in certain locations, Vegas being one, where it seems to be culturally acceptable; in many other cities, handing the desk agent a $20 at check-in will get you two fives and a ten in return, which you can count once you get to your booked standard room.