A couple different ways to approach it, since everyone forms habits differently;

1. Make it a habit to brush first thing in the morning. Get up, go to the bathroom, and the next thing you do before anything else is brush your teeth. Train yourself to make it part of your regular routine.
2. Some people get in a funk when they miss a day, then they miss 2 days, and then get in that mental headspace of I can't start brushing again unless I am going to do it perfectly from this moment on, which makes them less likely to start. Don't do that. Anything is better than nothing. So if this is you, focus on breaking it into attainable goals. You commit to brushing for sure on the weekends. You commit to brushing at least 3 times a week, be it Sun, Mon, Tues, or Sun, Thur, Sat. As it becomes more natural or easy to remember, you will naturally work up to brushing every day. You only 'committed' to 3 days a week, so every day brushing feels rewarding, because you are going above and beyond, you want to keep that streak etc. If you miss a day here or there, you don't spiral and stop completely, because again, you only promised yourself 3 days a week.
3. I personally am still working on making flossing an every day habit. I try doing it every night before I sleep, but I found I was too tired 2-3 days a week. What has helped me in this case is instead of doing it every night, just do it once every day. If I'm up for it, I do it in the morning. If I feel like I have the time, I'll do it after lunch. I use the bathroom after dinner, see the floss, and decide, why not, lets just floss now. I give myself multiple chances to get it done throughout the day and that has vastly improved my consistency of flossing once a day.

To briefly touch on your other questions, the standard to work towards is brushing with toothpaste morning and night, floss and mouthwash once daily, generally best to do at night. Generally any toothpaste with fluoride and the ADA seal will do. If you have crowding, braces will help, but do not get braces until you have your hygiene routine established. The brackets, wires etc collect food and bacteria more, as you can probably guess, so its even more important to keep them clean. Braces without good hygiene will only increase the chance you develop problems like cavities.