Whenever discussion of what chisels to get “first” comes up, there seems to be a debate about getting individual chisels or sets of chisels..
If buy a set you will usually get a good price (much lower than the combined individual prices) but you might end up with chisels that you never use… If you buy them individually as you need/want them you have to wait for delivery after you decide you need one more…
So the question is really one of what is needed. You need One chisel of moderate width for cleaning up joints, you need one that is fairly wide for all sorts of chopping splitting and cutting and beveling. And you need one for mortising if you are going to be making mortise and tenon joints.
One that is @ 1/2″ wide, One that is 1 1/2″ to 2″ wide, and a 5/16″ mortising chisel.
flat chisels come in several styles. Paring, Firmir, and Bevel edge, as well as But chisels…
A paring chisel is usually thin and is never driven with a mallet.
A Firmir is usually more robust and can take quite a bit of pounding.
a Bevel edge is nice to get into tight corners.
and a But Chisel is a short chisel.
A mortise chisel is usually thicker face to back than it is wide, to enable it to withstand extreme pounding with a heavy mallet.
there are also many different types of specialty chisels.
you can see I have a set of 4 mortising chisels, I use the 5/16″ out of that set the most. and I use the 1/8″ on the right and the 5/8″ to the left of them… the other 3 are mostly never taken out of the drawer.
so I say start with a couple and add to the bunch as you go.