Due to this card's low ATK, use "Xyz Territory" or "Xyz Unit" to provide a 1600 ATK boost, enough to bump this card's ATK to a respectable 3600. This can be enough to provide better durability in battle, while also making better use of its ability to attack directly. Also, "Xyz Unit" can allow a free use of this card's negation effect without consuming Xyz Material. Be aware that this card will negate the effect of "Xyz Unit", so use it when this card has no Xyz Material left.
Your opponent will probably try to crush "Lancelot" using a bigger monster, especially a Special Summoned one that doesn't require a card effect activation to be Summoned. So keep a Counter Trap like "Black Horn of Heaven" for such an occasion, "Lancelot" will not be able to negate it.
Have "Pyramid of Wonders" on your field before Summoning this card. Not only will it grant it some extra ATK, but it will also be able to save it from 1 destruction outcome. Since "Lancelot" does not negate the effects activation of Continuous Spells that are already activated, its mandatory negation effect will not interfere. Another good card for this strategy is "Intrigue Shield": being a Trap Card, the mandatory effect activation of "Lancelot" can be Chained, preferably to negate an opponent's card, and give it continuous protection. Use "Swordsman of Revealing Light" as a Material to Summon "Lancelot", giving it extra battle immunity.
Also, since "Numbers Overlay Boost" attaches monsters from your hand as Xyz Materials, one could use use the opportunity to attach a support monster like "Mezuki" (which can help keep this monster on the field longer) to this card, so its effect can be used effect as backup after it is detached.
Combine this card with "Splendid Venus" to make sure the activation of your Spell/Trap Cards won't be negated (make sure that if "Venus" is Summoned with a Spell, Trap or monster effect, do it without the mandatory effect of "Lancelot" interfering and negating said effect).
Also, combine this card with "Constellar Belt" to make sure the activation of your (LIGHT) monsters won't be negated too. But don't forget that it will also cover the effects of LIGHT monsters that your opponent plays against yourself.
If this card run out of Xyz Material, "Overpowering Eye" can be used to facilitate an extra direct attack.