The best online piano classes will develop your playing skills by using a combination of technical exercises and repertoire. It will introduce music theory concepts like chord structure, tempo markings, key signatures, and time signatures. It will also develop your ability to play by ear as well as to sight read. There are many online piano classes, also called online piano lessons, available and some are free of charge.
Before you begin looking for piano classes, try to assess your piano playing abilities. Some individuals are quite adept at playing piano, even though they have not had formal instruction. Often, they play "by ear", which means they learn songs by listening to them, not by reading music. Reading music is an important part of playing piano as it broadens the player's ability to play many different types of repertoire without having to hear the piece first, so many individuals who play by ear well still need further piano instruction to fully develop their skills.
If you have very little experience with the piano, you are probably a beginner. If you can play simple songs or read some music, you may be at the intermediate level. If you can read music fairly quickly, play songs with complicated left and right hand parts, and know a variety of pieces already, you may be at the late intermediate to advanced level.
Once you have roughly determined your skill level, look at different online piano lessons. Although there are fee-based online piano classes, explore the free ones first. There is a good chance that you can learn a great deal of the same technique through the free classes as you could through the fee-based classes. You should be able to determine the appropriate level by browsing through the lessons. Try to find a section that challenges your ability with one or two new concepts. Jumping into a level that is far too advanced for you will only be discouraging.
Good classes will be well-organized with clear objectives. They should be visually easy to read, as well as easy to understand. Often, the best courses will have lessons which only focus on one or two concepts at a time, provided in small segments so that you can practice the concept before going to the next lesson.
Some online piano classes have a great deal of text. Although there are many important concepts in music and piano which require reading and understand material, most students typically want to play as soon as possible. With that in mind, look for online piano classes which include multiple exercises and pieces to play as you learn piano concepts. Putting concepts into practice on the instrument will boost your motivation and help you continue through your lessons even with it gets difficult.
The best online piano classes are also self-paced. This means that you can move on to the next lesson, or go back to the previous lesson, whenever you feel you are ready. This allows you to work through the lessons as your ability allows, instead of at a predetermined rate. All individuals learn differently, and the muscles in your fingers will need time to acclimate to the new skills which you are learning.
It is important to understand that no class, no matter how well developed, can teach you to play the piano unless you practice the concepts. Your improvement as a pianist is directly related to how much you practice and how well you practice. Good practicing habits include working on specific sections of a song which are difficult, not just playing through the song over and over. Other good techniques are to work on pieces and exercises with one hand at a time and then both hands together and playing with a metronome in order to improve rhythm and overall time.