You will handle it just fine!
I had the same concerns and had a lot of mommy guilt that my DDs world would be turned upside down when the baby came (she was used to being the center of our world, and I felt bad about all the changes. But I can tell you, she ADORES her little sister. They are 30 months apart).
Anyway, I personally had a tough time adjusting from 1 to 2, but that was mainly due to PPD. My 2nd has also been a very needy baby and a poor sleeper from day 1, so it was hard to balance it at times. The biggest challenge has been giving my first born enough attention, which was impossible for the first several months because the baby is so demanding. Her behavior started getting unacceptable (she would bite the baby, pinch her, etc), so I knew we had to figure out a way to give her the time and attention she needed. It takes some planning to do that, but even 10 minutes of undivided attention after dinner (DH would take the baby to the other room) made a huge difference with DD.
If you have family nearby, that can be a help, too. My mother-in-law started coming once a week to take DD out for a special date, which also improved her behavior. I wish we had done those things far earlier than we did, because we had some really rough months in there trying to figure out a way to balance our children's needs. You will be just fine, it is awesome that you are already thinking about all of this now! I wish I would have done that. I suppose I should prepare myself to go from 2 to 3, because it is a pretty scary thought for me at the moment!