I advice you to check youtube videos for tuts and basics.. You can follow the practical steps to master Photoshop tools..
In my experience! Read, Study and Practice are the best keys to becoming a Photoshop expert. Do works of others and get the various idea to make yourself professional.
Youtube is the best. Though you will find some paid advance tutorial from some well-known online course provider. You can also read some blog as like: http://clippingpathserviceindia.com/blog/
I'd recommend youtube channel that's called 'Photoshop tutorials'. You'll easily find it just by searching, cause its official and marked. Very nice tutorials.