southern caribbean cruise on RCC

I have never sailed with RC before. Is there anything that would be good to know to get perks or a better rate? I have sailed 4X's with Princess and I feel like a pro with them, I find the Royal Caribbean sight a little bit complicated.I don't know anything about anything with RC so any helpful hints would be much appreciated. Looking at going on Serenade of the Sea for an 11 day southern caribbean cruise jan 21 2019. Is booking direct your best bet or with a travel agent? Discuss,,,

I looked at that same cruise for Feb 2019, ended up on Celebrity for similar itinerary. Have sailed with RCI x5. I have done better by using TA, get more perks than booking through RCI. Looking forward to visiting those southern islands.