Yes, that is a reasonable order to buy things. If you want specific advice on what to buy, you will want to say what your budget is.
Also, you might want to consider bookshelf speakers for all channels (other than subwoofer obviously), as it will save money over getting floorstanding speakers of the same quality. The deep bass, after all, is going to be handled by the subwoofer, so the other speakers need not deal with it. One can instead opt for either better bookshelf speakers, or a better subwoofer, with that extra money. It is what I did, and I had a pretty high budget (compared with most people). On a tight budget, I absolutely would go with bookshelf speakers all around. It is what I recommend for most people, though obviously what you should get will depend on your particular interests and situation.