As this deck is built around Dragon's Approach, you obviously want to cast as many as possible. But, before you do that you're going to want to set up an engine. There are enough lands and ramp spells in the deck to make the chance of having available to cast Neheb, Dreadhorde Champion on turn 3 around 50%, so that should always be your goal. Don't keep your opening hand unless you have a way to generate at least by turn 3 in it (two lands and a ramp spell, three lands, etc). The sooner you can cast Neheb the better.
Once you have Neheb on the battlefield, you're going to attack the poor sap who doesn't have at least 5 toughness on the board (in cEDH there will always be at least one). This is where you need to identify what in your hand is important and what is okay to discard. Almost every single time you are in this position you should be keeping two cards at most. I assure you that just one or two of the utilities in your hand are necessary in any given moment (with very rare exceptions). It's much more valuable to discard the cards that aren't as useful in the moment in order to dig deeper in your deck and get the extra mana.
After wheeling your hand and getting extra mana, try to find a way to cast a lethal amount of Dragon's Approaches. This is a "storm" deck, so you'll have to practice finding a winning line, but they do exist.
