Mika, one of the first things I'd do is to call IATA (go to http://www.iata.org
to find the contact details relevant for you) - at least here in Germany, it's not possible to just open up and start issuing tickets right away - the IATA accreditation was, at least when I went through the process, rather complicated.
If you're facing a similar situation as an agency would here in Germany, then I'd consider working through a consolidator for a while, where you book the flights in your own GDS (whichever one you decide on using) and then send the PNRs by queue to the IATA accredited consolidator, who then issues the tickets and sends them to you by mail (or issues an eTicket and just sends you the invoice
Some of the preconditions for IATA accreditation here in Germany are...
- having someone who's got a IATA/UFTAA Standard Diploma, not older than 2 years at most (the diploma, of course - not the person... )
- to get that, you need to have worked in a travel agency for some time and then take a written test through IATA
- with the application, you will need to prove the financial stability of your company - usually a bit difficult to do, if it's a new company: this is why new companies are usually either placed under a higher financial scrutiny, or simply not admitted to IATA
- Obviously, you'll need a GDS: since I work with the "big four" (Amadeus, Sabre, Galileo and Worldspan) on a daily basis, I'll say that - for someone who's never worked with a GDS before, Amadeus is the most intuitive and easiest to lean, while the others are, at least here in Germany, cheaper to use - of course, if you've been working with them for a while, the others are just as easy to use as Amadeus
- You'll need a ticket printer - and those things can get quite expensive
- You'll also need a safe, for safekeeping of the travel documents
- Next thing is, you'll need to put up either a large sum as security for IATA, or you'll need an insurance instead
Those are the points that I remember right off the top of my head - there are more... it took me quite a while to get everything up and running the way I wanted when I got my own agency... may it rest in peace... accredited with IATA.
As for working directly with airlines - some airlines will still offer you the choice of not working through IATA, but by being directly accredited with the airline - but I don't know of any airline in one of the alliances doing this. If at all, smaller carriers will offer this option, and only if you will be selling enough in volume of their flights.
Most airlines will not give you a direct contract with fares better than the published ones - at least not, until you've succeeded in selling a good amount of their tickets at published rates, which is usually difficult to do, but if you work at it, it's doable.
Ok... I have to catch something for dinner now and later pick up someone from the train station, so I'll have to stop here - if you think I can be of any further help, having gone through the whole excercise in 1998/1999, feel free to contact me...
In any case: good luck.