In Glasgow (and western Scotland) there exists the options of using either the train, bus, subway or one of the city's airports. In this article it is my intention to shed some light onto these forms of transport.
The main railway operator operating the trains to and fro Glasgow and the west is First ScotRail; First ScotRail provide a fast and frequent service from Glasgow to stations via Lanark, East Kilbride, Kilmarnock, Ayr, Stranraer, Ardrossan Town/Harbor, Largs, Wemyss Bay & Gourick. If the line is electrified (i.e. the Ayr line) then expect to travel in comfort and style in one of the new class 380 trains imported straight from Germany. If, however, the line is not electrified (i.e. the Kilmarnock line) then a class 156 DMU will most likely be put to use (they're ample though).
If travelling throughout the west of Scotland, note that Motherwell, Pailsey Gilmour Street, Kilwinning, Troon and Kilmarnock (among others) do act as interchange stations meaning that you do not go via Glasgow if you're travelling internally in western Scotland (thus saving money, but if you're ever confused then you should bear in mind that ALL stations in the west of Scotland - well Strathclyde - can be reached by one train direct from Glasgow Central).
Note that Prestwick Airport has a station (the Ayr train will stop here, but you can also go via Kilmarnock for the Stranraer train that leaves from there also stops at Prestwick Airport, it's the next stop after Troon; Stranraer services that go via Pailsey & Kilwinning, however, won't call at the airport). Please note that the production of certain flight tickets may entitle you to discounted or possibly even free rail travel for that day – you can double check with Ryanair, Prestwick Airport and/or First ScotRail to confirm if you’re unsure.
Glasgow Airport itself almost got a station (project GARL) but it didn't, albeit you can purchase a train ticket from your destination to Glasgow Airport (you alight at Pailsey Gilmour Street for the frequent bus connection; walking is also an option for the airport is reasonably close to Paisley).
Trains do operate in Glasgow via the Cathcart circle and the low-level railway system, this can be handy for reaching stations such as Exhibition Centre (serves the SECC) and Mount Florida (quite close to Hampden Park, as is Crosshill station). It is also possible to travel by train from Glasgow's second largest railway station Queen Street (15 minute walk from Central; there is a frequent bus service that connects the two and taxi services abound). Queen Street is used to access rail services via many Scottish destinations such as Falkirk (Falkirk High), Stirling, Edinburgh (Haymarket & Waverly) and Edinburgh Waverly may be used as a hub for accessing towns along the river tay/dee/don as well as Dundee, Arbroath, Stonehaven, Peterhead & Aberdeen.
Glasgow Central is also connected by train to English destinations such as Carlisle, Birmingham New Street & London Euston (the operator is Virgin trains). First TransPennine also offer a rail service from Glasgow to Manchester (albeit not Piccadilly station but the airport).
The main bus operator for this area of Scotland is Stagecoach. The main bus station for Glasgow is located at Buchannan Street and is operated by SPT; Scottish CityLink provide reasonably priced returns from here to many other Scottish destinations such as Fort William and Inverness. National Express and Megabus link Glasgow with many English destinations (most stop at service stations and these abound on the M 74 from Glasgow to Carlisle and the M 6 from Carlisle to Preston etc....) Note that most bus services are either circular within a local cohort or are destined to travel from one station to another (i.e. the 585 goes from Greenock to Ayr and then back again calling at Prestwick Airport, Irvine and Saltcoats as well as that of the other towns along the Firth of Clyde). For those less able SPT provide a service entitled MyBus, which basically provides a finite number of services per week on demand – although the drop-off points can be independent of bus stops (i.e. outside your house) the busses are generally restricted to Strathclyde (which is Ayrshire, Renfrewshire, Inverclyde, Lanarkshire and Glasgow city). The busses boast an orange livery and at one time the service was known as Dial-a-Bus.
Glasgow city boasts an excellent subway operated by SPT. Otherwise dubbed as the Clockwork Orange by locals the service is fast and frequent, plus less hassle than the bus or taxi given the grid-iron infrastructure of the Glaswegian streets. Note that the Cathcart circle (normal railway service operated by First ScotRail) services leave Glasgow Central on a frequent basis and certain rail services can be used in conjunction with the subway at Partick.
Glasgow is served by two international airports viz. Glasgow & Glasgow-Prestwick. Glasgow airport is situated between Glasgow and Paisley near a small Renfrewshire town called Linwood (plus Renfrew/Bridge-of-Weir/Johnstone). It is usually the busiest airport in Scotland and is served by many airlines such as easyJet, Fly Globespan, Emirates and British Airways. Destinations can be domestic (i.e. easyJet fly from Glasgow to Bristol), European or even in different continents such as North America (i.e. there’s a seasonal Vancouver flight operated by Fly Globespan) or Africa. The airport can also be used for accessing many Scottish destinations by airplane (services usually provided by Loganair or FlyBe); Glasgow and Stornoway are the only airports that can be used for accessing Barra in the western Hebrides, made famous by it’s “scary” landing experience due to the runway being nothing more than a beach. Prestwick airport, however, is a good thirty to forty miles away from Glasgow. The airport is in Ayrshire (between Troon and Prestwick/Monkton) but is reasonably easy to access from Glasgow by train or bus. The main flight operator is Ryanair but W!zz also fly from Prestwick. The airport, however, has a rich history and is said to be the only place where Elvis has set foot in the UK. Oftentimes military aircraft - such as Antanovs - can be observed at Prestwick Airport since the airport is not heavily used by passengers and can usually remain open in poor weather due to its proximity to the Firth of Clyde.