Train travel is in many countries the quickest and most comfortable way to get around this is especially the case in Europe where the networks are extensive, however they might not be the cheapest method of travel. In other parts of the world the service may be less efficient and buses are often quicker. The best guide to global trains is the Thomas Cook's European and Overseas time tables (Thomas Cook Publications, PO Box 227, Peterborough, England PE36SB). Which are worth their weight in gold if you intend to travel extensively by train they are available through most book shops in the UK.
Using trains can mean more planning than other forms of transport especially when trying to do a trip where a train runs once a week or is only rumoured to still be running. Try and obtain information about long distance infrequent routes at the earliest opportunity and be prepared to use other transport if the train doesn't appear. Sometimes it is not possible to get advanced details and the only thing to do is to turn up and wait.
Boarding a train without a ticket can mean you will end up with a large fine, remember the ticket inspectors will have heard all the excuses before. Travelling first class with a second class ticket is also a go way of upsetting people. Train tickets are often very cheap in the third world so if you need a break from the hassle go first class for a while.
Before queuing for a ticket decide if you want a slow or express train and the class you wish to travel in.
When obtaining a ticket it is often worth while reserving a seat on busy routes in some countries this is essential on certain trains. Get your ticket the day before you intend to travel so that you don't miss the train due to being stuck in a queue. When obtaining the ticket double check the train times with the ticket clerk in case the train only runs at certain times of year or days of the week, the time has changed or there is a impending train drivers strike.
When queuing try and check you are in the correct queue some stations will have different desks for different classes and local or national trains. Before you head to a station check it is the correct station some cities have more than one station. London is a good example having over eight main stations.
Travelling overnight by train gives you more time at your destination and also saves you a nights accommodation. You can choose to sleep on your seat if there are bench seats this is fairly comfortable or alternatively you can pay for accommodation this can vary from not much above the standard fare to being astronomical depending on the part of the world and the route you are taking. Most trains in Europe have seats that pull out in the compartments to form beds these don't cost any more but can only be used in less crowded trains.
The usual rules of travelling light and not letting your luggage out of your sight apply. There will be times when this is not possible for example a call of nature, in this case the best thing is to take any valuables with you. A cable lock is an excellent investment and allows you to lock your rucksack to a luggage shelf.
Most crime on trains happen over night usually there are particular routes where crime seems to be common place. In Europe the 'Europe by Train' guide is gives details of these routes and is also a bible to European back packers.
The first thing is to lock your luggage to the shelf above you. Some people leave their day sack beside them this usually contains camera, walkman, passport etc. A quick thief can grab it with out waking you. If every thing is in a large back pack cable locked above your head then they will definitely wake you if they try to grab it.
In some areas it has been known for thieves to pump sleeping gas into compartments and the occupants wake up with nothing. There's not much you can do about this if you are travelling alone except sleep with the window open and the door ajar.
The final method is for the thieves to befriend you and then offer you a drugged drink, you wake up with nothing but a head ache. So don't except anything.
Having spent weeks at a time sleeping on European trains I have never been a victim of theft but people have lost gear from neighbouring compartments so locking everything above you seems to work
Most stations have left luggage lockers in them in general these are safe but obviously some do get broken in to. If you see anyone acting suspiciously tell the authorities this time it may not be your gear but next time it might.
Food is often available on trains but can be of poor quality or expensive. Check out what is available in advance and if necessary take supplies. In hot climates remember bottled water. In the third world whole communities often inhabit stations and food is often easy to pick up on route from vendors at stations, as long as your stomach is strong enough.