It's tough in the NBA. First, there aren't very many superstars anymore, and it's basically impossible to win without one.
The Suns have made attempts in the past few years to get one, although some attempts more half-hearted than others. But we (and other small market teams like the bucks, tho the Suns aren't really a small market, but anyways) are always going to have a hard time getting the stars to come here
So I guess the answer to your question is, you either have to be prepared to overpay guys and take huge Luxury tax hits, but even that doesn't guarantee that the guys will go with you.
The other option is to draft really well and get a core together.
The parody in the NBA is really bad right now. All this stuff with the Celtics challenging the Cavs is comical. It will be Cavs/Warriors in the finals again this year, and probably again next year.
If the Suns can dump some salary, draft Josh Jackson and keep our young core togehter, I see us being a playoff team, but even then, can we beat Golden State? I doubt it.