Erasmus student looking for a flat

Hi guys, I will be doing my semester abroad in Riga - RTU, starting from September until January and I am currently looking for an apartment/studio. From what I've read, it is best to stay in the old town where most of the Erasmus activities take place. Could you please recommend me some reliable sites for apartment rental?

Also, can any of you give me some insights regarding the workload required for the RTU courses?

Thank you :))