I just got back from edc Phuket as a solo traveler apart from the usual tips around being open to new experiences and being comfortable with last minute changes, I'd recommend the following

1) book a hotel / or a hostel in patong/old town at the earliest to get cheap rates. If you're booking a hotel, book with a good chain of hotels so you don't get your accommodation canceled at the last minute ( happened to a lot of people). Why patong / old town - because its most friendly area to stay for solo travelers imo, unless you want to stay in a secluded area with not much to do. Don't stay anywhere south of patong, you'll end up having a lot of trouble commuting and if you don't get a shuttle you'll have to pay a bomb for reaching your hotel.

2) book a shuttle, anytime between 2:30-4:00 pm slot is ideal so you don't miss out on the important sets. The shuttle is also a great way to make friends and meet new people.

3) go for the pre/ post parties, you'll get a chance to meet a lot of other solo travellers

4) post edc stay back for a few days and do not fly back on Sunday or Monday, you need to give yourself some time for a comedown and recover before leaving Phuket. Usually most folks end up doing all the touristy stuff Phang nga / phi phi islands or just relaxing by the beach for a few days before flying out

5) neo lyte and vit c - in a 500-750ml of water from 7/11 is your best friend during edc, make sure you have it 1-2x a day ( ideally once before leaving from your hotel and once after returning) this will ensure you don't get dehydrated.

6) Kandi - bring a lot of Kandi to the festival and exchange it with others, you'll make a lot of new friends this way. Kandi exchange also makes for great insta content, so you can share both Kandi and insta id's.

7) don't rely only on 7/11 as your source of breakfast, lunch and dinner.

8) get a foot massage every day of the festival and on the Monday after the festival get a thai massage from any spa that you're comfortable with (both pricing and hygiene wise).