It is not very important to change the word that you don’t know by one that you know and is close in meaning BUT it is more important to use the Right verb ! As you should focus on constantly increase the number of verbs that you know in order to express yourself more and more precisely. Good luck

I always try to describe the word I'm looking for and it's usually just enough. And sometimes the word I was looking for just pops up :). I think you can employ this method for anything:). *want to say/express something