Before starting to explore the city, it's important you have some idea of where the party places are in Jakarta so you won't lose time going from one place to another.
The main areas for partying in Jakarta are the following: Triple 9, Nu China, Tipsy, Hangover, Eastern Promise, Murphy's Pub It used to be a trendy area for partying but as of 2015, it is not that happening.
Many expats live in Kemang though so there are some decent expat bars and small clubs.
What we usually do is to start partying in the south, and then head up-north, so that the more drunk we are, the wilder the party gets.
Clubs in Kota also close later so it's good to know if you still feel like partying at 5am.
Drugs, mostly ecstasy, crystal meth (shabu-shabu, called yaba in Thailand) and heroin (putau in Indonesian) are very common in Kota, to a point you cannot even begin to comprehend.
In some clubs, everyone is on pills, for instance in Sydney 2000. South of Monas, you have a majority of upmarket classy clubs and bars, though not only.
Clubs that are still open at 5am include Stadium (closed now), Mille's, Exotis, Pujasera.
Karaokes in Golden Crown and Colosseum are also still open until late.
Apart from that, the reputation of Kota as a dangerous area in Jakarta is over-exaggerated, especially if you compare it to the dangerous areas in western countries, where you would never walk alone.
Clubs in North Jakarta ALWAYS have prostitutes, usually a combination of freelance prostitutes and girls under contracts.
In the north, you also have to be very careful with taxis.