How to practice for solo queue

Normals? No. Your enemies and allies are both going to be worse, and there are no bans.

Here is what you do.

Go into a custom.

Fill your team with bots, and then invite 5 of your friends to play on the enemy team.

Try to win with these bots.

Once you can manage that, solo queue (having actual humans) should seem a bit easier to carry.