MILD is built around prospective memory. That is, remembering to do something in the future. When you set MILD intentions you’re not really setting the intention to realize you are dreaming, but to remember that you planned to realize you are dreaming, like as you say, telling yourself to remember to buy milk.
MILD mantras/inductions can be helpful to setting your intentions, and they work a whole lot better when you believe them and when you feel them. Just like you’re probably going to be more likely to remember milk if you have a recipe you really want to make that requires milk. You need to remember that milk to make cookies. You need to remember something that makes you realize you’re dreaming to fly. You really want to savor that warm gooey chocolate chip cookie, this recipe makes those really good cookies you had as a child. You want to fly because it will feel free, you want to be free.
Connecting a feeling makes it deeper, more important, and more rewarding to remember.
I feel like I’m always directing people to this thread and this post which I’ve found really helpful. It outlines the difference between implied and direct suggestions that may be helpful if you want to use MILD inductions.
I won’t spend a lot of time trying to summarize that thread since you can read it and it’ll do a better job that me, but depending on how your mind works and how you like to think, the “I will have a lucid dream tonight” can be undermined by the echo of doubt “but what if I don’t?” and then of course, the MILD is less likely to be successful because you don’t believe in it. If the direct suggestions do no work for you, you may have more success with implied suggestions ( such as “I love it when I have lucid dreams” or “I will write down my lucid dreams in the morning.” instead of “I have to have a lucid dream tonight”) because you might believe them more. Like connecting the importance of remembering to buy milk with your desire to bake cookies, I find it helpful to connect emotions or goals with remembering to realize I’m dreaming.
When I’m falling asleep I really like the mantra: “When I realize I am dreaming, I will X” Where I fill in my dream goal with X (like flying or whatever you want to do). To me this makes a great mantra because it not only helps prompt me to lucidity but it helps me remember and accomplish what I want to do. I also like to used “realize I am dreaming” over “lucid” because it says what “lucid” *means.*Connecting my goal to my emotions makes me feel more motivated to remember I’m dreaming, because I am more emotionally invested.
I consider myself a MILDer and one thing I find extremely helpful to connect my dream signs to (remember to) question reality. (As per MILD, I’m relying on my prospective memory: when I encounter a dream sign, I remember to question reality). Let’s ride the milk analogy a little further. I’m at the store shopping about to check out and I see a cute poster with a cow on it; it reminds me of the cow on the bottle of milk I like to buy! OH YEAH! I need to buy milk! How could I almost forget!? Good thing I saw something that helped me remember!
Just like that, it can be helpful to have a reminder in a dream that we wanted to realize we are dreaming (because we really wanted to fly and be free! or bake cookies!). Keep a dream journal and keep it well. Over time you can read through it and you may notice reoccurring themes or objects, these are dream signs. For me, I often encounter water in my dreams. Lucky for me water is pretty common in WL too, so when I see water, I (remember to) question my reality. A good reality check is one you remember to do, but a better one is one you’re triggered to do.
As usual, I unintentionally wrote a really long convoluted reply where I ramble, so, also as usual, I will apologize and remind you that I mostly speak to my experience and that your perspective and other’s perspective may differ. But I hope something I shared is helpful and gives you something to think about! 
