The Wordless Book is a very common method of teaching the Gospel to people, especially to kids or those who can’t read. It is thought to have been created by Charles Spurgeon in the 1800s in London as he was teaching children about Jesus. Child Evangelism Fellowship (CEF) has a free online training video with printable resources to help you understand how to use the Wordless Book effectively. This link will take you to their Wordless Book training page.
CEF has some additional information on presenting the Gospel to Children in an effective and understandable manner here.
For Teens and Adults
Dare2Share, an organization focused on helping students learn to share their faith without fear, uses an acrostic for GOSPEL to teach their students how to share the Gospel. Rapper and Spoken Word Artist Propoganda has released a spoken word entitled Life in 6 Words to complement this strategy. You can also download the complete Dare2Share App, which includes even more resources for evangelism (plus the ones already mentioned).
Life On Mission is the newest and probably simplest way I’ve seen to explain the Gospel. Life On Mission uses just through circles to demonstrate how we are all broken and in need of Jesus. This simple tool can be drawn on a scrap of paper or a napkin. There is a video from NAMB to teach you how to use the Life On Mission method, as well as a free app for you phone (and downloadable instructions if needed) that you can use to share with people.