Arriving in Kampala: the airport is rather small. You can get Ugandan shillings in the baggage claim hall. They buy dollars for 3600 UGX, but you can get 3630 if you haggle (which I did).

Once you have your UGX, you should buy a SIM card from one of the mobile phone providers. I chose MTN because of good reviews. Roaming costs are huge in Uganda, so it is better to use a local phone number and place your international calls through Skype. I payed 55.000 UGX for 3Gb of traffic plus airtime I will certainly not use entirely.