Some of you may have come across James Hill, who is a well-known current uke-performer, often with his cellist wife, Anne Janelle. Popular YouTubes include him playing Billie Jean (with his imaginary orchestra) or using chopsticks to play.
James has a gained a good reputation with his workshops, which he offers whilst he tours the world. He runs a well-explained, structured learning community site called The Ukulele Way. It contains instruction for complete beginners (called Booster Uke) and then works through online books with PDF worksheets and tutorial videos to take players from Beginner, then Intermediate to Advanced: Book 1 starts with the basics of open strings and posture while Book 6 ends with challenging blues, jazz and classical fingerstyle arrangements.
There are about a dozen free lessons & a support forum, which you can access for free. To gain full membership (which has over one hundred videos) you need to pay a monthly subscription. Or you can buy the individual printed books, if you prefer.
Here he is with Part One of his Chord Melody Crash Course, which explains how to play the chords to a simple song & also add in the tune, or melody (and here’s Part Two):