A great resource on all things train-travel related, with all the dos and donts. I've found it to be of immeasurable value. http://www.seat61.com/
For international timtebale connections I prefer the DB site. It's slightly better at finding trains than the SBB site. For bookings I tend to go the national sites of the relevant railways as there are often special deals and things that SBB don't know about. For example in Spain if you buy a return ticket it will cost less than two singles. Even if you buy a single and later buy the return leg, just showing the first leg will get you the discount on the second so that the tozal price will be that of a return. SBB don't seem to know anything about that and will sell you two unconnected singles even when you ask for a return.