I'm just wondering if it's ok to leave your clothes and things alone on the beach and go swim or should I ask others to keep them for me
Nowhere in Miami (or any other highly-populated beach).
You can buy small waterproof body safes (plastic bags and boxes with waterproof eeals) where you can carry important/valuable things, but don't leave anything on the beach that you would not want to lose.
Clothes are generally safe, but don't leave valuables like money, cards, phone, camera etc. Best to leave those in your room before you go swimming.
So if you wanna go to the beach you have to leave everything in the hotel!
Yes -- but why would you take a bunch of crap to the beach in front of your hotel anyway? what do you need?
Phone for the music and to take some pictures maybe lol
Those are not recommended if you plan to go alone, and go swimming. You can either leave them in your room, or not go swimming, or get one of those waterproof packs suggested above.
Why don't you read the post from Advisor Girl on the very first page of this forum that addresses this very subject ?
Listen to me. If its not tied down and locked in Miami Beach, it will be taken. We've lost 4 bikes here in 2 years and they all have been locked .People come from all over the world to the Beach and many don't have good intentions.