I played this game in my spare time and just concentrated on unlocking and starring as many characters as I could, all the while doing the daily challenges and progressing as far as possible in the LS/DS PVE tables. After awhile, I had a pretty decent roster of characters, but indeed most were at G8 if that high. I then picked a good team to work on, focused on gearing them, then made that my Arena team and rose in ranks, until I managed to save up crystals and could pick another team to work on.
I've done this over and over, and here we are. I have teams that can solo the HPit, HAAT, and I can bring in 20+million damage on the Sith Raid. All this and I'm 100% F2P. It takes a great deal of patience, and accepting that you're not going to be on par with people who have played for months/years. Why would you realistically expect to be? Even so, that doesn't mean you can't still contribute. Get in a good guild, help them and they'll help you.
All this said, I still do not envy a new player. This game is one very steep mountain to climb.