When learning i used reference images inside my 3d software, but once i started working i had to start using architectural blueprints to make models.
It all depends what you want to model, i got front/side/back reference images for inorganic objects like vehicles and items, especially for hard surface modeling. Humanoids and animals are harder to make because they dont look right unless you know your anatomy and how bones and muscles connect.
Cartoony characters are probably the easiest because you dont need to follow correct anatomical proportions, anime stuff... i dont know, never tried making one.
Biggest tip i can give is to not bite off more than you can chew, start something small and complete it from start to finish(and i mean, sketch, model, texture, rig and animate) rather than just starting a complex model and giving up midway because something isnt working out and you got a ton of polys to fix before you can even get to texturing part.