From where to where ?
These days, with the death of interlining you will, at best, get an on-line connection. BA to BA; EK to EK; UA to UA etc. This usually means one connection at the airlines home base. Through a 'code-share' you might be able to extend that by one addition connection. For example Geneva to London (BA metal but coded AA; London to Dallas (AA metal/code); Dallas to Austin (AA metal/code)
Pretty well all other connecting flights will be at a sum-of-sector fares, which could get quite expensive.
Have a look at
https://matrix.itasoftware.com from Google. There you can build an itinerary, using whichever airlines/sectors you can find, and it will give you a price. It does take some getting used to, so I recommend you only go there when you've got an hour or two to waste.
Good luck!