Manifestation isn't just about thinking something here and there and then it magically becomes your reality.
It's about creating clear steps that you need to apply and execute to make it a reality.
What exactly is it that you want to manifest? Create clarity around what you want in life.
Create a vision board, journal, and meditate about what you want from life. When you can actually see it, visualization will help you create the steps to get there.
Ignore the negative thoughts that will cause you doubt. This will only prevent you from manifesting your dream life. Positive thoughts only.
Ignore all distractions and keep looking inward. You can't appease everyone. So try to focus on yourself and ignore the outside noise.
Always stay humble, trust the process and give thanks to the manifestations that come to life. This is a mindset.