Kinshasa is an expensive place for sex, food, and hotels. In addition, there is no law and order because of civil breakdown due to many years of war, so be careful! There are a few nice places to go and meet girls, the best being 3615 on the main Boulevard 30 Juin. There you will find an outdoor bar and restaurant where they serve good pizza, and an indoor disco which is usually empty until well after midnight. The outdoor terrace is a good place to meet groups of well-dressed girls, but don't let the looks fool you, these girls are poor and desperate for money.
Some of them have an agreement with the owner of the place that anyone taking them to a hotel or otherwise must pay the girl $50! They will not tell you that though, until after the fact, and some will go with you for only 30 minutes and demand $50 after almost no sex at all. And you will get no sympathy from the police of anyone else, since it is assumed that you know that $50 is the going rate. However, some of the girls at 3615 are not part of this theft ring and can be had for considerably less. Most, however will want you to pay them a minimum of $25. It is hard to find good decent girls, most are hustlers hard on the hunt for cash.
Other places include: The Atmosphere disco at the Grand Hotel is a classy place, a bit pricey, but there are nice girls to be found there. Chez Temba downtown is famous for its Congolese music, and you will meet a wide range of people there, more of an older crowd since there is a $5 cover charge. Savanana on the main boulevard is full of sleazy prostitutes that are part of the same $50 sex ring, to be avoided, since drinks are expensive and the girls will order them and charge it to you or one of your male buddies without you knowing it.
Much better is the Casino on the main boulevard 100 meters from 3615. It is a small, classy dancing place, with a mixed crowd of foreigners and sophisticated local girls. There is $7 one drink minimum. Again, watch out for the $50 ring, since it is difficult to tell who is in it and who is not.
Also, be sure to hire one taxi from a reputable hotel to stay with you for the whole night wherever you go. Do not flag a taxi down on the street, since they are not marked and foreigners are frequently robbed at gunpoint this way. In short, Kinshasa is a dangerous, expensive place, with many people on the take, so take your time trying to understand the scene.