✔ 最佳答案
So many ways to present your opinion in term of using "I think", it's really depend on what kind of presentation you are giving out to your audience, says:
"Let's put it this way....."
"It would be my best recommendation..."
"From a professional point of view..."
"Most people would say /think... however, it is ....."
"Believe it or not...."
To improve your presentation skills, besides sentences / grammer, it is better to particular in others' presentation to observe and learn from others.
good luck!