It took me a bit of time to get into manufacturing, primarily time, and i even added an account strictly for it. I do everything from ammo/rigs/mods up to supercapitals/titans (with other friends for the larger stuff).

It takes a long time and decent investment to get into ship production, but as you get more experience, ship sales prosper in null-sec space for sure, but then you will need access to that via an alliance/corp.

I do agree with Shadow, you will definitely want to start with Ammo, especially medium projectile and heavy missiles. Those are the 2 most used ammo types in the game. However, you will definitely want to plan it out where you will sell them to make the most profit. Mostly level 4 mission hubs in caldari are great for to sell Drakes and Missile ammo, like wise in a level 4 minmatar area for hurricane sales and medium projectile.

I also recommend having no less then Production Efficiency 5, anything less then that is a waste of materials. Also depending on what you start out with, with PE5 you wont need any researched BPO to make profit.