No matter what look you do, it will always look amazing if your edges are properly blended! Here are a few tips on how to easily blend harsh edges.
My best trick for blending shadow is to use a matte eyeshadow colour close to, or just slightly lighter than, your natural skin tone and to apply it onto the brow bone and just along the edge of your eyeshadow. It will automatically help blend that edge and won't look like you've placed any additional product, but just have a perfectly blended edge! This trick is especially great for blending out harsh edges that, no matter what you do, are giving you are hard time and just wont blend out! Matte shadows can be hard to find sometimes, but have a look at brands like MAC and Makeup Forever... they do great matte shades!
Another great tip is to remember that blending is one hundred times easier if you blend with a clean brush that has no product on it... so have several blending brushes on hand. Brushes are expensive but are a necessity for great makeup! What's the point in having tons of amazing eyeshadow colours if you don't have the proper tools to make them work to their full potential? My favourite blending brush of all time is the MAC 217 (which I have three of)! It's the best for blending edges with ease, and also works great to deposit shadow all over the lid and into the crease!
Try out these two ticks and let me know how they work for you! You're guaranteed to be a blending master if you follow this rules!