Yea, what i do is i notice that i dont have much to say so i start talking about random crap which turns into rambling xD and that isn't that great, i would cut with no problem if i could but i make let's plays so if i cut a certain part of the video i will cut out the story of the game and what is happening too.
When playing a game, there's no real way to avoid silence because it will happen; it's inevitable. However, the best ways to avoid as much silence as possible is by commenting on things in the game. You can also talk about your life or what's happening on your channel, etc. Talking about the game is going to be the most beneficial part of your let's plays, but you can think of other topics before going on and just talk about them throughout the game. Because essentially, though you're playing a game (depending if you show your face on camera), you're still vlogging technically. Just have fun with it and let it come naturally. It's the best to form your personality for these types of videos.
For me it kinda comes naturally (without sounding big headed). I used to do drama where we would practice making up monologues in different characters - You could always try that when your home alone or in the shower so you dont get many wield looks xD
Ive also been on YT for a while now which various different channels but looking back at them - even if i could continuously speak, my early channels had very little personality and my voice just sounded boring. I find it always helps to extend your personality and almost become a cartoon character of yourself to make it a tad over the top but without going too far because it can just be seen as annoying.
If all else fails, dont be scared of jump cuts - used in the right way, they can sometimes be better than straight up talking.
Good Luck
