First suggestion would be to get a copy of Hydrobuddy. It’s free. While it’s not without faults, it is the best one available at that price. It has some built in “example” formulations which you can tweak.
Second suggestion is to consider enrolling in something like, http://www.npk-university.com/classes.html . Harley Smith will give you a good background into the nutrient ratios and why. Plus, a bunch of more information over the course of a couple of months. Unfortunately, it appears that the price has increased recently from $95 to $250. About $20 per class.
There are reference material available that provide optimal nutrient ratios for growing different species, I can’t recall the name off-hand. Something red-book, something. When I remember, I’ll update this.
With some of the background, look at some of threads here and elsewhere such as Theories on proper NPK cannabis ratios. There are numerous DIY formulas on the interwebs. With the background and software in hand, you’ll be able to determine a suitable set of macro and micro nutrients that will work for your situation. In fact, there is enough information available to recreate formulations of some of the favorite manufacturers using the before-mentioned software (many manufacturer’s in this industry like to claim they use a proprietary blend of “magic” and unicorns).
Edit:
Looks like there are some prerecorded short courses now. Nutrient Management, for a bit less dollars at $64. Downside, you can’t ask questions since it’s prerecorded.