OK, very brief rundown, though please don't hesitate to ask for further information if I don't make much sense
.
If you are coming back to Guildford afterwards, then ask for a return to London Bridge. If you are staying at London Bridge and not returning then ask for a single to London Bridge. If you are not sure about whether you need off-peak tickets or peak tickets then speak to the clerk as you buy your ticket and they will advise you as necessary
.
If you have a single it'll be marked 'Guildford to London Terminals', and if you have a return, one will be marked 'Guildford to London Terminals', and the other 'London Terminals to Guildford' - Keep both parts of the ticket together until you get to London Bridge and the ticket barrier there decides to retain the part marked 'OUT'.
Regarding the service you need to travel on from Guildford, the departure screen in the ticket hall will display the final destinations (and in some cases, 'via xxx' and/or 'fast'/'slow'/'stopping' service), the platform they are due to depart from, and the timetabled and expected (live) time they are due.
Look on the screen (probably at Guildford it will scroll between pages - so look at page 1 first), and working down from the top look for 'London Waterloo' - some services are slower that others (and I believe the majority of fast services will depart from platform 5 there but please check this when you travel!). If there are several showing with departure times close to each other then ask a member of staff which is quicker - in my opinion, South West Trains staff are very helpful and will tell you
.
To find the platform, there will be signs to guide you in the right direction, however if you get lost, then do ask a member of staff who'll tell you where to go.
At Guildford (if they are working), are automated announcements announcing the time of the train, its destination and its calling pattern (i.e. what stations it calls at en-route). There will also be a departure board on the platform listing the next 3 departures from that platform, and for the next one its calling pattern and other useful information about the train (such as how many coaches it has). Do listen to the announcements, and do read the board - sometimes the platform may change at the last minute, or the train may be delayed.
When you get to Waterloo, exit the platform by walking to the front of the train then going on the concourse there (do not go downstairs into the Tube!), there will be signs directing to Waterloo East (the staircase and escalators are next to Burger King, and opposite platform 6 roughly if I recall) there is a glass dome over the top reading 'Waterloo East' and it is only a short walk. Go up the stairs and along the passageway until you see the ticket machine and a slope down to platforms B, C, and D. There will be a screen above the tunnel down and look for a departure on platforms A or C (these are the trains that run to London Bridge).
When you find which platform has a service that departs first then go down to that platform (for A you need to turn left and follow the main tunnel a bit more before sloping down - it will again by signposted, though). Check the departure board on that platform to make sure that the first stop for the service is London Bridge and if so then it will be the right train. Waterloo East also has the automated announcements as at Guildford to help (but these are not as reliable as at Guildford).
8 out of every 9 trains leaving Waterloo East in the eastbound direction call at London Bridge (in the general off peak pattern) but 1 every half an hour is fast to Kent (normally leaves platform C at 26 and 56 minutes past the hour) so make sure your service isn't this odd one! If you have any doubt, then there is (for most of the day) an information desk at the top of the slopes down to platforms B, C, and D so ask the member of staff there for assistance about which service to use.
The train to London Bridge is only 1 stop and takes at most 4 minutes. Once arriving, follow signs for 'Way Out' to exit the station
.
In any case however, if there is a train waiting in the platform when you arrive and you are unsure if it is yours do NOT run and get on it - it is likely you'll end up somewhere different to where you want to be! Let it go, and check the next one goes to where you want it to rather than risk it and end up in a place you don't want to be
.
Hope this helps, and if you need any more help then post again!
! I believe that all eastbound trains from Waterloo East (ie. all those not going to Charing Cross) call at London Bridge. You could try searching at 
