Selective color can be a pretty neat effect - as long as it's done on the right images, and not overdone...

I think out of 87 picks (the good ones) from the engagement portrait session, only 3 had this effect. It's a great one, don't get me wrong, just don't be 'that guy' using it on every other photo.

Like many things, there are about 100 different ways of creating the effect. Lightroom does it simply in two ways - the adjustment brush and the HSL panel. The adjustment brush was used on the top two, HSL on the third.

Adjustment brush technique is done by using -100 saturation and painting over everything you don't want colorized. You can then go in and create another brush point (is that what they're even called?) and boost some saturation among the colors that are left.

The bottom photo can't be done with this technique due to all the leaves on the ground. Well, I guess you could - only it would take you about a day to select the ones you want. Just select the tones you don't want and drop the saturation down to nothing - that will take care of it. You may need to go back in and paint away some stray tones, but for the most part, you should be good.