I am facing difficulty with toefl speaking sometimes I blank out on what to say next. How do I improve at it?
I am able to do better in the longer speaking sections because we know what to speak from the passage and the conversation. But, in the smaller speaking question where we have to come up with reason, I am having a bit of a trouble.
How do I practice at home and improve?
Get a speaking partner to help you out (even friends, parents, anyone who has some time to spare basically) Ask them to read out the questions, play the tracks, show you the passages, etc. and time your preparation and record you speaking. Sit and evaluate your recording later. For the speaking task-1 you can just give a list to your friend and ask them to ask you a question and prepare for 15 seconds. Try to come up with 2 reasons, that’s it. Rest of the things you can make them up as you speak. You’ll definitely see what is to be improved once you do 10-15 questions. Also, keep in mind, this is an English test and not a lie detector. I would sometimes tell a story as if I was a character from a movie. For instance “what is the most difficult situation you’ve faced recently, how did you overcome it”, I would say something like “I got stuck in the Himalayan base camp for 2 days because there was an avalanche” 
Hey thanks for all the advise!
Does it matter if we do without a speaking parter? Currently I am only setting the timers and playing the tracks
Yea totally, but you’ll have to multitask. I have tried it and I had to start a timer there, start the recording here, change the display, etc. But if you record the 45 second audio, and revisit it right after speaking and make points, you should be good.