If you're on a tight budget then don't tip. Tipping for beauty services isn't that common and most people know how poor students generally are.

It's very easy to get around in the Netherlands in English including using the trains. I was just there again over the weekend. I stayed in Leiden and visited both Venlo for the Floriade and Keukenhof. You'll be able to buy a ticket on this route right up to the time of departure with no problem. Some trains on popular routes can sell out - for example, the night trains between Paris and Italy. Trains for special events like Oktoberfest in Munich can also sell out. But most of the time, you don't really need to book in advance. In your case, there are at least two train per hour through the day; You'll need to make a train change en route, but it's an easy trip. You can find schedules and prices here: http://www.ns.nl/en/travellers/home

Minimum wage is something like 1300. Rental of a simple room with shared facilities will be 300. For that price you're all the way at the outskirts in not a very nice neighbourhood. Mobile services vary immensly. Internet, say 25 euros. Health care, mandatory in this country, 90.

As a student that is just about what I would live on, including rent, food and a lot of beer. I was paying €310 for a room all including, and prices have risen a bit since then (2 years ago). That amount will be enough if your willing to settle for a room (25m2) and sharing facilities. A flat near(ish) the centre will cost you a minimum of €600, and that would be very reasonable and you would be lucky to get one at that price, but not impossible. You can get TV, internet, phone all across NL for €40. I spend about €200-280 on food alone, but do like good quality food. If your willing to live on the outskirts of Groningen (Beijum, Lewenborg), you can get a furnished house for €400/month.