Does Ward affect my own spells and abilities?

No. Ward only triggers when an opponent targets the permanent, so you can freely target your own Ward creature without paying the cost.

What happens if an opponent does not pay the Ward cost?

The targeting spell or ability is countered and has no effect, even if it would otherwise have been valid.

What is the best Ward card?

By popularity, Ward is among the most-played Ward cards — see the full ranked list above.

Best Ward cards in MTG

Ward: Whenever a permanent with Ward becomes the target of a spell or ability an opponent controls, that spell or ability is countered unless its controller pays the Ward cost.

Ward acts as a soft form of protection, taxing opponents who want to target your creature with removal and often making cheap removal inefficient. Unlike Hexproof, it still lets you and your opponents target the creature, but at a cost. It is excellent on value creatures you want to keep on the battlefield while still being able to enchant or pump them yourself.

FAQ

Does Ward affect my own spells and abilities?: No. Ward only triggers when an opponent targets the permanent, so you can freely target your own Ward creature without paying the cost.
What happens if an opponent does not pay the Ward cost?: The targeting spell or ability is countered and has no effect, even if it would otherwise have been valid.
What is the best Ward card?: By popularity, Ward is among the most-played Ward cards — see the full ranked list above.