My tips:
Man in Seat 61 - Read the ManinSeat61 website before buying anything. His site gives very specific instructions on highly traveled routes, which you can easily see. https://www.seat61.com/index-mobile.htm
Say no to RailEurope - When you Google train tickets, RailEurope or other third party resellers will be your top hits. Do not use them! They are not the companies that run the trains. Always buy tickets from the actual train companies, like Deutsche Bahn, OeBB, etc. See #1 for more info.
Railpasses are a luxury - Railpasses are more expensive than point to point tickets in nearly, if not all, instances. With Railpasses you are paying more because they want you to think it is easier to travel with a document that you just wave at the conductor. Folks, that was in 1970. In 2022, if you have a Railpass you have to jump through all kinds of hoops to make reservations, forcing you to interact with the actual train company anyway. And good luck getting customer service from the company that sold you the pass. If you buy a rail pass, you will be paying 2-3 times what you should have paid for normal point to point tickets purchased from the actual train company.
Buy advanced point to point tickets for long distance travel. So here’s the deal. The train companies sell tickets in advance, months ahead, at a great discount for a specific train at a specific time. There are a limited number at each price and once those sell out, the tickets can be purchased at the next cost increment. If you buy your tickets at the train station on the day of travel from the ticket counter at the station, you will pay full fare. No one does this. Note - many places like RailEurope will use these full fare prices into tricking you to believe that passes are cheaper than tickets. Don’t be fooled.
Second class is very nice - First class is a waste of money. Second class is spacious and very, very much ok.
Look into regional passes/tickets - The actual train companies often sell regional tickets or passes which are a great value. One example is the Einfach-Raus ticket or a Bayern Ticket. When making local travel plans, research these.
Make a seat reservation - when you buy your ticket from the actual train company, do yourself a favor and spend a few Euro on a seat reservation. Sometimes this is required anyway. It’s always nicer to sit than stand.
What are your tips?