I think there are basically 3 really good options for what to buy on I1:
- 1 fighter
- 1 transport, 1 infantry
- nothing; save 10 IPC
My standard has been to buy the fighter. As long as Germany attacks Egypt (with the bomber), you can be reasonably sure that Italy will get collect both NOs on their first turn, giving them 21-23. So you don’t need to save for the carrier on I2, you’ll have the cash. With the fighter buy, you’ll have the carrier loaded as soon as its built, instead of having to “borrow” a fighter from Germany. Plus you can use the second fighter on I2 if need be.
The trans + inf buy is my preferred one, since it gets land units into Africa as quickly as possible. But it depends on what the UK does on their turn. If they have bombers, I’d rather not split my fleet up to protect the transport, so I wouldn’t buy it in this case since the fleet will be in sz15 at the end of I1. However, I find that often the UK loses its bomber on their first turn when they clear out the German Baltic fleet (so they can land both fighters on a carrier). In this case, as long as the Egyptian fighter isn’t still hanging around, nothing will be in range of the transport so you can go ahead and buy it without worry.
Lastly, saving your income could be good if the fleet is being threatened by bombers and you want to plop down multiple ships at once for protection when you return to sz14.