I recommend getting something with a plastic motor/fin can for your first rocket or two. It makes assembly much easier, and the screw on motor retention cap is a reliable system that's easy to reload for a second flight.

An Estes Nova or Patriot would be a good pick.

After that, go for a kit that ditches the injection-molded plastic parts and uses simpler components, such as laser-cut wood and paper tube rolls. This will teach you more advanced construction and assembly techniques. Then begin working your way up in size to the high-power rocketry.

Of course, there are a lot of directions you can take with the hobby. Some people stay small and make rocket-gliders. Others like to build the biggest rocket and fly as high as they can. Others stick as much of an electronics payload onboard as they can, and often times will design their own electronics for the purpose. There's been a surge of interest in thrust-vector-control, using servos to angle the motor for stability instead of relying on fins.

Rocketry is really the only hobby where not even the sky is the limit, and you can work in as many sub-disciplines as you can think of. Just find something to build, and keep building. Your curiosity will keep you moving in the right direction if you let it. (Though your wallet may sometimes complain!)