For the US to really start getting better WC results, the #1 goal has to be getting and maintaining a Top 7 ranking which gets you seeded in a World Cup. 7 of the 8 seeds advanced, with 5 reaching the quarterfinals and 3 reaching the semifinals.
Aside from the obvious of developing better players, there are some ways that scheduling can help achieve this goal:
1) Convince CONCACAF to switch the Gold Cup from every 2 years to every 4 years. Between two Gold Cups plus WC qualifying in a four year cycle, that's way too damn many games against s***ty CONCACAF teams. Replace one of the Gold Cups with an 8 team invitational tournament involving the US, Mexico, plus two teams each from UEFA, CONMEBOL and CAF. Ideally you get teams ranked in the 15-25 range--low enough that they are beatable but high enough that it improves your schedule strength.
2) Get as many friendlies as possible (and even make a few of them full international matches) against top 25 nations.