noun
Refers to the manner or method of using something; often implies that the outcome depends on how it is used.
この道具は使いようによってはとても便利だ。
Depending on how you use it, this tool can be very useful.
お金は使いようで人生が変わる。
Money can change your life depending on how you use it.
使い方 is the more common and neutral word for 'how to use' or 'usage'. 使いよう often carries a nuance of 'it depends on how you use it' and is used in expressions like 使いようによっては.
Compound of 使い (the continuative form of 使う, 'to use') and 様 (よう, 'way, manner').