Low fare airlines amaze me. Companies like Ryanair often offer fares for pretty much nothing where you pretty much only pay the airport taxes. Even their regular fare prices are amazingly cheap.
Travellers are very lucky to be able to take advantage of some of these fantastic offers being made by this new breed of airline.
Service: Low fares do not necessarily mean a poor service, but you are likely to receive less service than from a top tier airline.
Risks: There are probably more risks, like your flight being cancelled or not receiving the kinds of benefits you might receive from a full fare airline like Thai Airways, eg if you miss your flight, or a connecting flight.
Low Frills: Low fare airlines do normally mean low frills. Part of their budget saving measure are normally to remove perks like free food and drinks. Frequent flyer type programs tend to be out as well.
Fine Print: Be sure to read the conditions of the low far airline to make sure they fit in with your requirements.
Baggage Limits: In particular, always check the baggage limits. Low fare airlines often will have smaller baggage limits than full fare airlines. You don't want a nasty surprise of a hefty excess baggage fee when you get to the airport. This would put a real bad spin on the holiday before it even begins.
Airport Transport Costs: Another point to consider is the overall cost of your travel. Often low fare airlines will use small airports that are located outside the main areas. This can mean that services like trains are not available. Getting to where you want to go from the airport will often cost you more than the actual flight. This can be double ended as well, because your departure airport might also be an out of the way airport. Depending on which country you are in, taxis may not have such low fares.
Book Early: Budget airlines begin with a low fare that increases, sometime significantly, as the plane is filled. Make sure you book early so you get the cheapest deal possible.
Shop around: Check some of the other domestic airlines. A competitors' matching service may not have been as popular and could be offering a lower fare. Unpopular flying dates, times and seasons will generally provide cheaper fares. As with accommodation, you will likely need to get in early if you want to book for a special event or public holiday.
Checking Baggage: Low cost airlines may not provide a check through service for your baggage. You may need to clear immigration, collect your bags, and check in again if you have multiple flights.
Try take advantage of these low fare airlines, do it right and you will have more spending money for your holiday!