Giving plant-based diet a second shot

I adopted a plant-based diet in 2008 which started out a lacto-ovo and eventually evolved to vegan.  I ended up suffering from major vitamin deficiencies and was ordered to add animal products back into my diet by my Dr. In 2011.  My blood came back watery thin and was not oxidizing properly (was not turning red when exposed to the air but instead a strange orange).
​Over the last few years, I have done more research into plant-based diets and what could have gone wrong with mine.  But it is difficult to find credible sources that agree with each other nutritionally.
​I want to give the plant-based diet another shot and do it right this time.  Are there any sources you veteran vegans rely on to ensure you meet  your nutritional needs?  Any other advice would be welcomed also.