What is the trick to get a tourist visa of more than one month when you are over 35 years old?
No trick, legally -
Current (valid within 6 months) passport
Passport size photo
flug1980x, you've posted this in the Russia forum: is that the country you're wanting the visa for or is it a different country?
Additionally, your citizenship is a factor: what passport do you hold?
As previously stated, tourists visas are what they are so best to check the requirements for your citizenship/passport and follow them. "Tricks" are not advised - and not legal - for trying to get around them.
A multiple-entry tourist visa for Russia costs a little more, but probably worth it for anyone who might want that option: https://washington.mid.ru/en/consular-services/citizens-usa/visa-to-russia/tourist-visa/.
One way to extend your time of stay beyond 30 days is to apply for a private visa, which gives one up to 6-month stay. If on a multiple-entry tourist visa, you might have to do a "visa run" to another country (Finland works fine, especially if you're in Saint Petersburg - their Allegro train is ride pretty nice, efficient, and affordable).
A multiple-entry three-year visa (tourist or private) costs exactly the same as a single-entry visa ($160, if applied for in person at the consulate vs. mail-in or in-person application via VFS).
No specific tips or tricks otherwise - except noting that processing times have been reported to reach up to 30 days.