First, let me make it very clear. Nothing teaches you how to handle losing streaks better than experience. I had to endure countless losing streaks and blown accounts before I could mentally handle them.
The key to handling a losing streak comes down to simple risk management, if your account survives the losing streak, and you know it can, then your overall mentality will greatly improve and the way you approach the market each day will be in a mindset of longevity and not revenge.
If you have not experienced more than 10 big losing streaks, then be prepared for a difficult ride ahead, the experience is necessary.
To summarize it, experience and risk management is simply all you need to survive a losing streak.
A HUGE mistake that most make is changing strategies in the midst of a losing streak. If it was raining into your house in a middle of a storm, would you just burn your house down and buy a new one, or would you instead fix it and find a way to survive the next storm?
(This is just my opinion, not financial advice)