Actually I have a few friends who did already some translations but from English to Polish. I am already preparing myself to also take part in some projects when I achieve proper rank on forum. What I can tell is that you should track topics in bounties sections and just check every new if the translations are available, past 2 weeks there were about 10-15 translation offers per week so it is quite often. From these translations, polish language is in around 20-30% which is quite rarely, russian is encountered more often so it  should be easier for you to find something for yourself. Many bounties require from you to have some experience, so don't be upset if some people will disagree for your cooperation at first. Wait patiently and find bounty manager who will be able to hire you for your first work. After that it will be much easier for you. Having evidence of your previous work.