So you are now amped up and want to do it. You want to go vegan and consume a plant based diet. I'm going to say slow it down. Anything worth doing is worth doing right. The juice is worth the squeeze. Good things come to those who wait. Etc...
The biggest impact most will see is to let go of dairy. It is also the hardest for most, so I say let it go first. What is your go-to dairy? Cheese? Milk? Ice Cream? Yougurt? What ever it is, finish what you have in your house. That is correct, finish your biggest dairy vice that you have, and prepare to let it go.
If it is milk, do some research on a suitable replacement. Rice milk? Almond Milk? Soy Milk (I am not an advocate of un-fermented soy, but for the time being it is the lesser of two evils)? Make your choice. When you are done with the old, bring in the new. Live with it. Understand your decision. Take your time.
If you are like me, and your choice is cheese or yougurt, finish what you have and think about what your new snack will be, and why. Fruit? Vegetables and Hummus? Nuts? What would you like and what will you be able to live with? Make your choice and live with it. Enjoy the changes it has over you and your well being.
This is a one change at a time thing. It is a lifestyle change. To fully appreciate it, you have to understand and appreciate the change OF it. You need to understand how something made you feel before and the way you feel afterwards. Don't get me wrong, somethings will be worse than others. You could quite possibly have cheese withdrawals. I'm not kidding. Give each change 2 weeks. 2 full weeks.
If you feel you need soy to get you through giving up dairy, so be it. However, be experimenting with alternatives like almond milk & nut based cheeses (these are ridiculously easy and unbelievable delicious to make at home). Find something outside of dairy and soy that works for you in the long run.
After you have successfully kicked your dairy habit, work on your dependency on meats. One thing at a time. Red meat & pork, then poultry, then fish. I can not stress how important it is to take your time at this. Understand how YOUR body works, and how these foods make you feel.
Some people find it easier to stick to processed soy replacements while they are learning to live without meat. If this is the case, again, so be it. Discover what nutrients your body requires to successfully eliminate meats from your diet and learn to work this in, while lessening your dependency on processed soy products.
If you do not already, a great tool to track your nutritional balance is to not only count calories during your transition, but to watch your carbohydrate, fat, protein, and sugar intake. This can be an amazing way to put nutritional balance into perspective. Start before you make the first change and use this a tool to guide you. Hit your minimum calories, carbohydrates, fats, sugars, and proteins and do your best not to exceed your limits.
When you've gotten through dairy and meat, you will have eaten your way through what was left in your home and replaced them with alternatives like almond milks, fresh fruits and vegetables, legumes, nuts, and whole grains. To see what you have accomplished at a very personal level is amazing. Look at your refrigerator and pantry. Love what you have done for yourself.