Analogies are quite common in everyday, informal speaking. If anything, however, Americans tend to use the same tired analogies ad infinitum. Here are a few examples:
Jim's old car sticks out like a sore thumb when it's parked on the street.
Sally's joke went over like a lead balloon at the party last night.
Harry throws a baseball like a little girl.
You're repeating yourself like a broken record. [This one would be understood by only folks who know that a record player's tonearm can get "stuck" in a certain location on the record and repeat the same snippet of music over and over again until someone gives the tonearm a little push to get it unstuck.]
My point is that you needn't be self-conscious about using analogies; just make sure you put some thought into them before parroting the same tired analogies, as above.
Furthermore, I do not see anything wrong with starting a sentence with
It's like . . ..
Perhaps when using analogies in writing, you should put a little more original thinking into their construction. Compare the construction of the following two analogies.
I told Dick to stop trying to get a date with Linda, who is way above him in attractiveness. I said, "It's like beating a dead horse!"
When I found out Dick was still trying to get a date with Linda, I said to him, "Dick, my man, you are barking up the wrong tree! Joyce is more your speed. At least she's accessible."
I am not claiming that number two, above, is a great--or even original--analogy, but as you can see there is no need to include the word like in number two's analogy. We get the picture that Dick's efforts, like those of a hunting dog, are totally inappropriate and futile if they are focused on the wrong prey, so to speak. (The dog may think he has treed a raccoon, when in fact it's just a kitty cat.)
Additionally, at least in number two, there is no need to use the word like, since the analogy is implied, and it communicates that Dick, in his attempt to get a date with the lovely Linda, has set his sights on the wrong gal.