If you look for a simple way to beat mayweather you're not going to find one. It's very hard to land a clean shot let alone land a hard enough shot to put him in any danger.

What's needed isn't so much strategy rather speed and and good defensive skills. The day Mayweather loses if it ever happens it will be the kind of fight that could have gone either way, with a good argument for both fighters. If you go out looking for knock out blows Mayweather will find it easy to counter punch or avoid damage until you start to slow. A jab must be well utilized to counter Mayweathers speed, a jab that matches Mayweathers for speed and power. If you can win the battle of the jabs you are part way there. Mayweather throws a lead right when his opponent least expects it or is off balance. you'll need to constantly faint to keep this from happening and keep him guessing. His body shots are hugely under estimated so your body needs to be trained hard. Cardio and speed should be priority in training.

It would be a messy tactical battle with both fighters spoiling leaving mayweather with good cause to complain.