In Russia, mostly women appointed as a judge. They tend to take the side of the mothers. Provide documents about your income, about what have good housing, where the child will be comfortable. If you have a prestigious job or a good position, it is also + Documents that you are not involved in the criminal or administrative liability that you do not have a mental illness, and others. The more - the better.
The state duty for the trial court is about 9 euros. A lawyer is not needed if you have a lot of documents.
Good luck!