Reading all of the Sarah J. Maas series - A Court of Thorns and Roses (ACOTAR), Throne of Glass (TOG), and Crescent City (CC); this would be the order I suggest reading the series in. 

The TOG prequel (Assassin's Blade) I would recommend reading after the second book (Crown of Midnight). Books 6 and 7 in the TOG series are often read in tandem - you can find a list of the chapter orders online - I would recommend this highly, it was an amazing reading experience!