I started kit building over 35 years ago.my first kit was debolt champ and I built over the plans andmy wife still laughes as I built 2 left wings.

Get both kinds of ca.thin snd gap filling.get yourself a number of clamps.go to harbor freight or ace.get dap filler to fill little nicks dents etc.ger a dremel tool and sears scroll saw. Make sure your buiding board is level! I usually get a piece of homosote from a local lumber yard.it makes using T pins easier.one tip I learned was to take the clear covering on monokote or ultracote and save it to use to cover the plans.
And get a zona saw and make a little miter box.

Also 1/4 and smaller drill bits .I bought a few that are very long to get at firewalls and help make contro rod holes inthe fuse.

I have been building all my life.gradually add all the things mentioned on the posts.and most importantly get organized so you can find these things when you need them.and have fun