@juicey09
I didn't buy turnips this week, so no doubt there'll be massive turnip prices!!
I've got 4 stars. How do you get to 5? Victoria says I've got too much stuff lying about the island
There's some hidden formula. You need enough trees but not too many. You need enough stuff placed round the island but not too much. You need to tidy up dropped branches and weeds. You also need to use fencing a bit.
The message about stuff lying around is to do with dropped stuff (e.g. items you've dropped from your inventory, DIYs you've dropped on the beach etc.). Pick it up and stick it in your storage or make tables and benches and drop it on them instead, then it doesn't count.
Once you've picked up, go back and ask Isabelle for an evaluation. It's a real time thing so if the lying about stuff was the issue, you'll instantly be five stars. If you're not, do what she says and then check back again after you've done it. Rinse and repeat.
It's useful to visit five star islands to get a feel for what did it for others. There are plenty around here and people enjoy showing them off so that shouldn't be a problem 
Good luck!