Sending to a wrong address could only lead to two reasons, first, you really have been wrong with it and you copied the wrong address. Second, you're a victim of a malware that changes the copied address.
Did it happen to you?
No.
How comfortable are you every time you transfer to a remote address?
100%.
I'm checking it many times before pressing that send button.
Would you be more comfortable using a helper?
Yes but after that, he/she should learn from it because if a mistake is being done, I might even be accused that have replaced the address by a newbie.
What do you use today to mitigate this risk?
Buy at dips and accept that the market is always volatile no matter how careful you are.