A lot of people try getting on a vegan diet for a few months, then get off it because they experience negative symptoms like weakness, lack of energy, feeling hungry excessively, and meat cravings. Many get their blood checked and see they are lacking in some vitamins. This happens because people don't get their daily recommended dose of each vitamin. Most vegans don't eat enough spinach and broccoli and sesame seeds everyday, so after a while they start to feel negative effects. I hate eating broccoli and spinach, and don't want to focus too much on my daily dose of vitamins, so I take vitamins and supplements to make things easier.
Calcium:
Take one tablet a day with a meal.
https://www.amazon.com/VegLife-Marine-Calcium-Tablet-Count/dp/B001L81SEC
Zinc:
Take one tablet a day with a meal.
https://www.amazon.com/gp/product/B01HNFJS16/
B-12:
Take one tablet a day and put it under your tongue until it dissolves. I like to chew it then put it under my tongue so it dissolves faster.
https://www.amazon.com/Jarrow-Formulas-Methylcobalamin-B12-Supports/dp/B002FJW3ZY/
D3 and K2:
Put one tablet under your tongue after chewing like the B-12. You can get D3 from the sun, but some people don't go outside often.
https://www.amazon.com/gp/product/B0187RWP3M/
Iron:
Put one tablet under your tongue after chewing like the B-12
https://www.amazon.com/gp/product/B00NV5UTM0/
Iodine:
All you need is three drops a day to get your daily recommendation. Also put the drops under your tongue and wait for it to absorb.
https://www.amazon.com/J-Crows-Lugols-Iodine-Solution-Pack/dp/B00E3B49R2
Selenium:
From Brazil nuts, all you need is one or two nuts a day to get your daily recommended dose of selenium
https://www.amazon.com/gp/product/B00DT74I86/
Creatine Monohydrate Powder Micronized:
You don't really need creatine but it helps if you want to build muscles and strength. All you need is one teaspoon a day with a meal.
https://www.amazon.com/gp/product/B00E9M4XEE/