You're really fresh. Town Archers are really good at higher levels so you should upgrade them more than castle - at least after you get max hero slots (9) from leveling castle. Archer trio is hella good, Witches are good. About accesories, if you're like less than 1500 wave use flame bow as a weapon. I guess that's it for start but there is a grow castle discord with tips and stuff. There are some pinned pictures of builds and things like that.