9-12 month old SUMMER MUST HAVES!? First time mama needs help!!!!

I’m a first time mama and my little boy will be 9-12 months during this summer (currently 8 months).

I need to buy him new clothes like TODAY because he’s pretty much outgrew everything!

What clothing items do you recommend I buy? How many of each? Shoes? Sandles? Hate? Sleepers? Shorts? Etc. i worry that I won’t buy the right things, that he’ll be too cold or too hot, that I will have too much of one thing; and not enough of the other thing.

I literally know nothing! 🤦🏻‍♀️

Also any stores you would recommend would help as well. Thanks so much in advance!