Actually I try NOT to level to fast these days. I have 8 toons, the latest is a Marauder at lvl 29, and I spend a lot of time round-robin with my other toons for gathering-missions, crafting stuff for upgrading my toons etc. So, before I even begin a new toon, I typically craft every hilt/barrel, armoring and mod from level 9-58, with the last ones at purple quality. Not to mention I add a lot of credits for crewskills, I have a ton of purple and blue grade companion affection stuff. So, nowadays I easily increase affection to 10.000 almost immidatedly.
Now, thinking of your post, I remember grinding away at two toons for 4 months or so, and it seemed veeery slow.
The trick for the new player is to go to wz's as much as possible, very easy to level if you even remember doing those missions. I didn't even start with wz's before 3 or 4 months ago, and I enjoy it. If I had known this, I'd use wz's a lot more, even as a F2P when I started out, now I'm a sub. But the most important isn't to level as fast as possible, as I've iscovered. The goal isn't level 60, but the way leading to level 60.