The cake looks great for a beginner! The only things I notice right away are the palm leaves and the flower that's being covered up by the fondant border. You are using marshmallow fondant, yes? Your palm leaves should either be gumpaste or fondant that's been let to dry for a few days. That way they can stick up and look full instead of droopy.
With the flower on the top tier, I would have not used that at all or just made a bunch of small flowers or blossoms to scatter on the top tier around the name.
Overall you did a fantastic job!
Edited to add the tiki faces look awesome!
AYep looks great I would just add try to make it easier but still interesting. What I mean is, all that fondant mixing will wear your hands out and increase production time. So in making cakes try incorporating other things so you don't have to work so hard and the cake won't dry out so fast. Like candy! It gives it texture but you don't have to kill yourself making it. My SIL did a cake same theme and she thought me this lesson. She used those pirotte cookies that looked like beach wood. Fish candies, can't remember what else. So for theme cakes I try to incorporate other items. It's clever and sometimes cuts down on work.
I'd suggest covering your corrugated cake board... presentation is everything!
The cake looks great, I love the colors!
Thanks everyone for your tips. It's going to help me out with my next cake which will be a sneaker cake for my husband's birthday this weekend.