With "Double Summon", gathering the Fusion Material monsters will be much faster, saving yourself a costly turn.
If this card was destroyed and winds up in your Graveyard, it can be a pain to re-Summon. One easy way to do so is to use the effect of "Herald of Creation". Since "XYZ-Dragon Cannon" is a Fusion Monster, it will wind up in your Extra Deck when the effect of "Herald of Creation" is used. Then use "Return from the Different Dimension" to bring back the Fusion Materials of this card and fuse them to bring back "XYZ-Dragon Cannon". Alternatively, use "Pot of Avarice" on it. This way it lessens the Deck thickening. A few searchers could also be returned (that will no doubt have been used to search out the pieces for "XYZ") to bring out a whole new set of Fusion Materials.
This card can combo with "Dark Armed Dragon". When a DARK monster is discarded for this effect, it can then be banished for the effect of "Dark Armed Dragon", destroying 2 cards for the price of one.
Use "Forced Requisition" to destroy 2 cards (one in your opponent's hand and one on the field) for each card that was discard.
Combine the top two combos to destroy 3 cards for the price of one.
While "XYZ-Dragon Cannon" is under your control, activate the effect of "Thunder Dragon" to add 2 "Thunder Dragons" to your hand. So, 2 cards can be discarded for the effect of "XYZ-Dragon Cannon" instead of 1.
If all three Fusion Materials are in your hand at once, "Frontline Base" and "Ancient Fairy Dragon" can be used to Summon all three in one turn.
If there is a "X", "Y" and "Z" in the Graveyard, "Machine Duplication" can be used on "Geargiano" to Summon 2 more for a total of 3, and Tribute all 3 to Summon "XYZ-Dragon Cannon".
One of the most efficient ways to summon this card is to activate "Unexpected Dai" to Special Summon "X-Head Cannon" from the deck, play "Union Hangar" and add either "Y-Dragon Head" or "Z-Metal Tank" to hand with its effect. Summon the one you added to hand and use the Hangar's other effect to equip it with the other one from the Deck. Since "XYZ-Dragon Cannon" says to banish the above "cards" you control, they don't have to be in the Monster Zone, so you can just banish all 3 right away to summon it.