Hello and welcome! Feel free to post any models you make along the way, you never know who it may help, and at the very least it will help bolster confidence in this new hobby. If you already have the three piece set, you’re certainly well on your way. Everyone has their own ideas about what the perfect tool set should be, but when it gets right down to it, if it works for you and helps make your models easier, more power to you!
That said, I personally used the three piece set for probably my first 20 models. After that I found I needed some smaller tweezer nose pliers as well, for helping shape/fold/grip very small pieces, the set I bought was from Xuron, linked here on Amazon.
After a while the edge of my flush cutters started to go dull from use, so I did some research into the hardest edged flush cutters I could hope to get, and ended up getting these chrome vandium steel (high carbon content means a stronger metal) with induction hardened edge, linked here on Amazon.
Beyond that, a drill bit set (already had it on hand) for rolling different sized cylinders, some 5-second-fix UV activated glue (plastic) to help with loose or broken connections, a fine tipped pair of rigid tweezers (this tool helps with conical shapes), and I’m a bit of a perfectionist so I laid down about $45 USD on a doming set for helping to make more “round” domes, but I realistically got by for a long time without that particular tool.
Hope that all helps some, have fun!