Filing a trademark seems easy and relatively cheap. And I'm planning to do so to protect my new brand despite it not being particularly valuable. The tricky part - the part where you have to decide what to write - is writing a description of goods and services.
The best advice I found was this:
Even attorneys will differ in their approach to writing a Goods and Services description. For small businesses that have just one or two trademarks, we recommend a Goods and Services description that includes the broadest possible commercial description, a narrower description including any unique aspect of your stuff, additional descriptions if other words might be used to find your stuff, any pre-approved goods and services from the trademark ID manual.
This is aimed at the US but, from what I understand, should probably apply equally to other jurisdictions. Having read the above, I am planning to write the description of my product like this:
Computer software for premufication of spodangles; computer software; data processing equipment, computers; computer software.
I.e. narrow unique description, broaad/generic one and a couple of applicable descriptions from the standard list.
Is this a good approach? I am not hiring a lawyer because filing a trademark doesn't make business sense if the cost is more than a couple of hundred USD.