I have been playing AWS for a while (started in 2011) and i find it extremely difficult to effectively manage airlines in two games at the same time. Right now I am in two (MT and JA) - but only because all the slots are gone in my HQ in MT so it's pretty easy to manage. Usually, I stick to the one game at a time (for example, I will not be joining the DOTM that will be starting soon).
Honestly, my suggestion would be play BW for a few days to get the hang of the game, and quit MT and JA (haven't looked at MT yet, but I know you are up against a pretty experienced player in JA - and will struggle to make money). And then I would start DOTM and a less busy area of the world (S. America, Africa, eastern europe, central asia, etc)...usually it's easier to start from the beginning of a game than the middle of a game...alternatively, i would keep either MT or JA and leave the other.
* full disclosure - I am in the Elite Worldwide Alliance in both MT and JA. The other player in your airport is part of the Elite network of alliances so please consider that when making any decisions about starting or leaving game worlds.