what size is the tank you are doing? Are you going to do a fully planted tank? How many watts per gallon of lighting are you doing? What is your substrate? Lotsa questions I know...but I have learned that they are all important for a healthy planted tank!
Also remember that every plant is different in regards to their requirements. Hornwort for example is a easy care plant that requires low light. Some plants require high light.....
For my tanks, I fertilize with 6 different products from the Seachem flourish line.