Replacing a sky in Photoshop can seem a little daunting but it really shouldn’t be. Serge Ramelli is the master and a very good teacher, most of what I know so far about image processing I learned from watching Serge’s videos.
Using the wrong sky at the wrong moment of the day is the ONE mistake to not do on sky replacement. Check out my skies that you can get for free and use them using the technique that I show. – Serge Ramelli