The easiest way to get to either Nairobi or Kampala from Kisumu is probably by Akamaba Bus Services. They have two direct busses in either direction between the two capitals that pass through Kisumu around lunchtime.
If you are travelling from Nairobi or Kampala the bus will stop here for you to grab some lunch from one of the many cafes opposite the office. There is also a waiting room here with toilets out the back which have came as a welcome releif on my last trip between Kampala and Nairobi.
The office is situated not far from the train station.
Boda boda is the name given to the bicycles mainly used here as a means of transportation when getting around, upto the main small town its hard to get a car or a matatu. Thanks God the govt. has finally made a tarmac road, we hope now there will be buses plying this route