To have God on your side is better than having the right strategy. But can you imagine what will happen if you have both?
The problem with "I just trust the Lord" is that if you are working the wrong strategy, you won't know it for several years. And by that time you will have given as many as 5 or 10 years of your life to something that was never going to work in the first place.
Trust God, absolutely. And if you have mental limitations, trust is enough. But if you do have a good mind, part of trusting God is to use the amazing brain he gave us.
"For God has not given a spirit of fear, but of power, love, and a sound mind" (2 Timothy 1:7). Bill Bright called this the "sound mind principle."