Hi There,
With an airline they are going to be looking for someone who is capable of serving the public in a friendly and helpful manner, whilst looking smart and presentable. A combination of a smart skirt or trousers, with a smart shirt or fashion top would look smart.
Group interviews should be approached from a team focussed point of view, rather than seeing people as competition. Usually in these types of interviews you will be expected to answer a range of questions about working in customer facing environments and assisting customers, as well as answering questions about any previous similar roles you have undertaken, so think in advance of examples you can give of good service given or how you have relatable experience. They will also usually ask you to complete tasks in groups so that they can observe how you work with others. These usually consist of games such as ‘who can build the highest tower’, and you should try and ensure that you show in the excersise that you can both direct and take direction, and just ensure that you keep conferring with your colleagues and checking they are doing ok.
When questioned individually just remember to keep calm in the interview and listen to what you are being asked. Be honest, and if you are struggling, don’t be afraid to ask for a few minutes to think. Be sure to have some questions of your own lined up to ask your interviewer, and remember, if you don’t get the job don’t see it as rejection- you wouldn’t want a job that wasn’t suited to you, so it’s important to be honest.
Good luck!