Renting in Tallinn - What to look out for?

I'm a freelance developer and will arrive in Tallinn this month to stay/work for a year or longer. My first task will be to find an apartment, so I wanted to read up on everything about those.

Several posts here already mentioned the usual suspects to find them - kv.ee, city24.ee. I was wondering if there is anything specific I should ask about/look for in an apartment, since I'm not used to living this far north. If relevant: my budget will be <€500 a month, maybe €600 if it's a real gem.

Any tips and recommendations are welcome!