Pirate Ships are a challenge, but fighting them will be your main income: they're relatively simple to capture with Gamma PACs, and if you capture them with a decent amount of health intact you can get 100,000 creds for each one you hock. The enemies in X2 fight stupid, so Mandalays and Bayamons are meat for you. Once you do that mission you can use your M4 to fight some pirates. Following the plot will give you some perks there are some simple ways to turn some extra profit from it too, such as selling the shields and weapon from the transporter ship you use to pick up Mi Ton in the second or third mission that's a big one and should let you buy an M4 ship, not to mention you also get a freighter (albeit a damaged one) for that. I can still give my answer: getting ahead in x2 isn't impossible, it just takes patience.
You know, the subjects discussed in this thread so far haven't really fit with the original topic.