I feel my MILD technique is weak and isn’t too much effective, i think it is because
i don’t have good visualization skills, although i don’t get too much motivation sometimes.
But sometimes i visualize that i am having sex with a girl i like (kinda embarrassing talking about this)
I can’t visualize that i am flying or doing another thing because it may be too complex due to my low visualization skills.
What should i really visualize to make me lucid?
Moved from General Lucidness. 
For the MILD technique, you should visualize yourself in a dream you had previously.
You should visualize yourself doing that dream and then realising that you’re in a dream then visualize yourself doing what you would like to do in your next LD.
Why do you visualize yourself having sex with a girl you like? - probably because you like the idea, you like the feeling you get, you like how it makes you feel, in one word makes you feel good!
That’s my advice. Feel good, feel nice, feel awesome, feel joy and visualize things that makes you feel like that, that will help you to have LD’s. Once when you experience flying in LD’s, when you’ll have real memory and impression then visualizing flying will not be hard, it’s going to be like remembering how to drink a glass of water…