It’ll get easier as you gain experience. Like Buda said, experience provides some insight into what will likely work and what won’t, so that alone save a lot of time. That experience can also lead to getting stuck in ruts that mostly work, but don’t blaze new territory, which is a problem for down the road, I suppose.
I’ve found that solutions to design problems usually stem directly from analyzing the problem itself. What’s the goal, who’s the target audience, what will appeal to them, what’s the client really concerned about, what’s the timeframe and the budget, what successes have others have solving similar problems and how did they do it. etc. Get a good handle on these kinds of practical things and it tends to really narrow down the problem to something much more focused and manageable.
You’ll probably also find that, unlike design school, inspiration is often not as valued by clients as just getting the job done on time, within budget and to their satisfaction. If you can make it look good besides, so much the better.