Originally Posted by
Machka
- Set the bicycle up correctly for you.
- Make sure that the saddle is the right width for you.
- Make sure that the saddle is the correct position for you.
- Get padded cycling shorts, and ensure that the padding covers your sitbones.
- Build your core and upper body strength so that you sit lightly on the saddle with good posture.*
- Ride lots and build your fitness.
* On the point about building your core etc. ... when you ride, put some of your weight on your feet. Don't put all your weight on your butt. This does take a certain degree of fitness and core strength. Also make sure you are sitting on your sitbones.
And if you're a new cyclist, it can take a couple weeks before you feel all right on your saddle.

Good advice!
I'll add that I use higher end Performance Bike padded shorts. Chamois Butt'r chamois cream seems to help too.
I was sized for a seat at a Specialized store and bought the Avatar Expert accordingly. My Fizik Aliante VS is a tad narrow, but seems OK.