WRT what was already mentioned about Char 4, I think you should consider which crafting sets to play first to help your alts level a bit easier. Also, there's a sticky topic on which companions are best for which crafting profession as far as bonuses go.
Keep in mind that my playstyle will be different from yours (I'm a trooper first, smuggler second, jedi third kind of guy). If I had it to do again, I'd go biochem first, then cybertech, then armormech. I'm only mid 30's on my main guy, but that's where I see the most gaps in my alts' (and companioins') gear.
The giant PITA is fitting slicing in there for pattern collection. I went cybertech, slicing, UT and had to buy all my green materials. I got stuck once higher level materials weren't on the GTN.