Checking in
Instead of filling in a form, save time by simply giving the staff your business card.
Non-smoking
If this is very important to you, choose a non-smoking hotel.
I always request a room on a non-smoking floor. (A non-smoking room can easily get smoke from the passage or other rooms.)
Regarding non-smoking rooms, In countries where smoking is popular, I suggest ensuring your booking includes 'non-smoking room' in the title, rather than in the comments. They will be less likely to overlook it, and you will have more bargaining power if they give you a smoking room. And when you check-in, confirm that you have a non-smoking room.
Quiet!!!
I always request a room on a high-floor, in an attempt to reduce noise from the street.
A room on the busy-street-side is noisier too, so a request for a room not busy-street-side may help too.
Breakfast
Breakfast at your hotel is convenient, especially if you are not familiar with the location. And you can often get it included for little extra cost.
Swimming Pools
To protect swimmers from diseases, swimming pool water must be disinfected and chlorine is usually used. I check the free chlorine in swimming pools before I will swim in them. This is a quick, easy test with AquaChek pool test strips
I have tested many hotel swimming pools in the last few years and usually the strips indicate no free chlorine, so I do not swim.
Hotel reviews
I read reviews to get first-hand information about the hotel and location. I prefer reviews from booking sites - these should only be from genuine guests. But even these can be unreliable, or optimistic: my rating of a recent stay was much lower than most reviews I read.