Many players find the task somewhat difficult, however it is more than possible to reach those levels in a decent amount of time with the right management.
Firstly, you need LOTS of cash to actually buy said items. Then you need to know where to collect xp to level up, because these levels require A LOT of it.
To level up often, one of the BEST working solutions is to beat 10 rivals, reload the game, then beat 10 rivals again, reload the game, and on it goes. This will give you a ton of xp to level up until level 140 and you will gain lots of xp. If you start early at 90 level and up, by doing so you will not only be able to level up fast, but you will increase the amount of money you get from beating ten rivals. Another working suggestion, while you are gaining levels, is to get and keep a boyfriend who will give you a cash bonus. Once you have dated you boyfriend for several days and up to a week, he will give you +40% increase in all cash you get. This is a seriously big bonus. By the time you reach Level 145, you can get around 5.500 It Girl Cash per 10 rivals beaten. But take care to have the highest hotness clothing. La Shalle clothing line is recommended for use in beating 10 girl rivals and can be bought in It or Miss from your clique members or top 10.
Then, buy the Cruise. Once you have reached level 140, the 2 parties at the Cruise (do not ask how) give more xp than it is written in game stats. By winning those parties once daily you will be able to reach the next Heavenly Heights whithin 5-7 days. You can also win parties at Tokyo, but they give reletively little xp compared to the Cruise parties. The Cruise parties must be your FIRST priority.
It takes around a week or less to open a new room.