When Do You Listen To That "Skinny" Advice?

"Don't eat after 7 pm."

"Eat every 3 hours."

"Lose weight first, then weight lift."

"Go to the gym everyday!"

"Meal-prepping is key."

Have you heard anything like this? Any advice that makes you so confused about but intrigued that it could work?
If you've read other posts from me, you know that I struggle with weight and weight related issues my entire life. I've recently-and by recently I mean a few years-really gotten interested in nutrition and exercise science. How do body builders or athletes know exactly what to feed their body or exactly what muscle to work to get the result that they want?
Sorry for all the questions.

I follow a lot of [fitness-inspiring] people on Instagram that always show the work that they do, the food they eat and their 'tips'. People that have started from where I feel I am and grow into the athletes that they are. This fitness model, Brittany Dawn, started a few years ago wanting to change her life and so she did. Of course, on Instagram we only ever see the highlights of a persons journey, but she has built an industry for herself based on what she learned.

Instagram: @brittanydawnfitness
She's my fitness inspiration for doing it yourself! 

Where do people start? Do they just try all the different advice until they stumble across the thing that works for them?

What is the secret? Don't worry about answering, that is a rhetorical question because the most important rule to remember for a healthy mindset is that, everyone is different-every body is different and reacts differently to things.
Of course, everything depends on what you are wanting to do with your body. Just everyday health, bikini competition, body building, etc.
I have experimented my entire life; weightlifting, eating every 3 hours, I was anorexic (and still struggle with the mental aspect of it), running, boxing, counting macros, etc. For me, the second I start weightlifting, the number on the scale climbs very quickly.
I absolutely HATE running. But for my body, it works wonders. I feel healthier, my stress level drops, and it leans me out. What I have found is that even though I hate running, it works for me so I need to learn to love it.

I'm working on loving it and luckily T likes running with me. It's great future Husband and Wife bonding time. :)

I personally have the hashtag #sweatingforthewedding on my mind. I want to feel my absolute best in my wedding dress and love my wedding pictures. I want to be able to complete the 5k I've signed up for with a friend in June (without dying and maybe even beat my 5k time of 30 minutes!). Not only that but I want to make a healthy mindset a part of my life for the long term. I want my children to play outside on the trampoline or ride their bikes. I want us as a family to go on walks or hikes. I want us to cook healthy foods and teach/learn the value of good nutrition.

The only question is...where do I start?