Karma yoga should not be divorced from other forms of yoga. Other forms of yoga should be supplemented by karma yoga, and also karma yoga should not be practised in isolation; it too should be supplemented by other types of yoga. All the different yogic paths mutually reinforce each other. For example, karma yoga done with even moderate success will help one to gain more success in meditational practices. Improved concentration through karma yoga will help lead one to real meditational experience. In turn meaningful and more profound meditational experiences from raja yoga, kriya yoga, etc. will help one to more successfully practise karma yoga. It is a cyclic process, each helping the other. While meditational techniques help to highlight inner problems, both mental and emotional, karma yoga also helps to bring these problems out into the open and finally exhaust them.
Asanas and pranayama not only help improve meditational techniques, they also help one to perform karma yoga more efficiently. And in turn if you achieve even a reasonable flow of concentration during your working day then your daily practice of asanas and pranayama and meditational techniques will also undergo a vast improvement. You will automatically have a spontaneous flow of concentration throughout the practice, allowing the benefits to really manifest. This in itself is an important reason for trying to practise karma yoga. The heightened experiences and peace that one will come to know through the daily yogic practices will in turn make it far easier to practise karma yoga, which leads to greater relaxation and concentration in daily activities which again will make the daily yogic practice program more fruitful. It is a continuous elevating process. This applies to all raja yoga systems including kriya yoga.
If you are devotionally inclined then karma yoga can be directly linked with bhakti yoga1. Karma yoga will also prepare the mind for jnana yoga2, which requires an intense, concentrated mind. Karma yoga is a path for everyone. It supplements all other yogic paths.