You can go for an online preparation course. Which one you choose is not important. Spending too much time choosing which material to study is not advisable. So do not waste much time and mental energy tracking their work and juggling their sources.
No, this is what you need (generally spinning around redistributing all the difficult work that goes around preparation yet isn't simply the preparation):
-One round of prep through some material, all the way.
-Somebody to manage your progress - right answers, wrong answers, weak concepts, strong concepts.
-Somebody to deal with your time - Hours spent day by day and such.
-Availability (having your books and material all over the place. Metro rides, transport, when you travel, and so forth). This is significant for a working professional.
-Somebody to arrange the material for you.
-Opportunity to go over the material over and over (unrealistic in contact classes).
In all of the above, online courses are much better for working professionals. While you study conveniently and all your energy is focused on your preparation, the software gets all your things organized for you.
After you have done one set of course material thoroughly and still feel the need to improve then you can start looking at other supplementary courses and study material.