Make reservations through Open Table which lets you search by location and type of food, and a specific time.
You can also make reservations directly with participating restaurants.
Make reservations ASAP, since the most preferred restaurants and dining times fill up first.
My recommendation is lunch. Not because it’s about half the price of dinner, but because dinners usually sell out first and you are likely to have more choice at lunch.
Be aware of the dress code at upscale restaurants, which may require jackets for men and not allow jeans, sneakers, t-shirts or flip-flops on anybody, men or women.
Many restaurants do not participate during the weekends, so do not expect a Saturday night prime time table.
If your restaurant of choice is in the Theater District, you might not get a table in the peak pre-theater hour
Review the menu in advance, since NYC Restaurant Week menu choices are more limited than the full menu. If you have eating restrictions, you may be limited even more.
Reservations early in the week are easier to get than later in the week.
Reservations for lunch are easier to get than reservations for dinner.
Be sure to mention Restaurant Week when you make a reservation, and when you arrive at the restaurant.
When you are seated, if you are not offered the Restaurant Week menu, ask for it.
Tip the wait staff based on the regular price of the meal, not the discounted Restaurant Week price, especially if you’ve had good service.