I'm currently employed by Nokia as a software developer, but as a hobbist photographer I might get some chances to get some paid jobs and earn a little money. We are talking about a ridiculously low amount (as I'm doing mostly free works for my own pleasure) -- I'm quite confident I won't make more than 500€ per year, not even enough to pay back the costs of my expensive hobby.

I'm not even sure I want to ask for a fee, but in my website I might just suggest an offer in the measure that the "customer" liked the final photos. But it mostly depends on how this side income is regulated by the law.
So, my question is: what actions do I need to take before starting such a "business"? Do I need to keep accountancy for the money I get, or can I just sum it up to my Nokia income and pay taxes on the whole yearly income? And what if I decide to go for this "free offer" service?
Needless to say, I don't care about VAT deductions for the photographic equipment I might need buy -- I still consider it my hobby.
Thanks for any advice

Alberto