Iceea's advice is good. Cons are the best fun! I used to love going with my kids, some of my cousins and a couple of friends who were into that stuff. How I first got involved in that community is a long story for another time, but it was something I did for a good forty years until I moved to somewhere that makes getting to them impossible without more resources than I now have. Good days, good days.
Cosplay was never my main interest, but my kids loved it, and would often go as a matched set of something such as Tolkien characters, and the cousin whose mundane profession was actor was very helpful with their costumes, and had great fun with his own, as did the cousin who was an electronics engineer - he was forever tinkering with odd alien costumes and things with weird internal lights, which in those days was unusual.
My own interests were more in the writing side and in filksinging, and I was usually to be found in the filk room or at a writer's panel or workshop when I wasn't shepherding the kids. (The writer's workshops were where I met Ursula le Guin, and several other interesting people). Mostly for costumed parts of the programme I went in my reenactment gear, both because it was easy, and after all the effort I had put into my handmade mail I liked to show it off, plus it looked impressive if I was doing security. The other thing I sometimes did was to run workshops on realistic combat for the fantasy writers. It was rather fun to get them into armour, swinging a heavy sword, and see for how long they could keep up witty repartee.