>>5444358Get one of the 3in1 creator sets(just pick the ones with a color scheme that you like). They have great piece variety and are generally a pretty good start to a collection. Additionally, you might want to pick up a handful of mixels as well. They too have great piece variety, just on a smaller scale.
But this is assuming that you want to make your own creations of the of the parts from the sets. If you have no interest in mocing then just pick up sets that look like fun to you.