Hours of study and practice for years, rehearsals with the whole band, more and more rehearsals and hundreds and hundreds of live gigs.

The performance itself is 10% of the involvement in time and energy. What you see and hear when you hire them is only the tip of the iceberg.

At the top of the list is the front person. The leader in the band is the most important member during performances.

* Is he experienced at 'reading the audience'?
  Can he cope with annoying customers with class and win the audience in any situation?

* Is he a good performer?
  Does he move well on stage?
  Is he able to communicate and generate audience participation at will,  or intuitive enough to refrain from doing so when appropriate?

* Can he be sophisticated enough for the highest society celebrations and corporate events if this is what you are aiming for? Can he   be friendly, accessible and easy going to chat and laugh with you and your friends if you throw a small casual do?

On the musicians side, experience is very important...

1. He has an extensive and varied repertoire of songs and can cope with most requests.

2. He plays at the volume appropriate to the room and the occasion. Inexperienced musicians almost always play too loud and annoy your guests.

3. He keeps his solos short unless otherwise advised. Inexperienced musicians either are afraid to solo or act as if your guests had paid $75 to come and see them at a concert hall... you can't stop them. It usually ends in very long tunes which lose their impact and empty the dance floor.

4. He can change gear instantly on request and is skilled at following the directions given by the front person. When you perform with a highly professional singer/front person each performance is different. Parts of the song can be lengthened or shortened at any time. The dynamics in the song can be calmed down or heightened at unusual places. Endings can be shortened or lengthened, etc. etc. The leader should be a master at reading audiences. The band follows his directions from the first to the last note. It is always a great experience following him.

5. He dresses appropriately for the occasion and in accordance with the client's request. This has one exception to the rule.. When moving and setting up equipment a pro will rarely be dressed in dinner suite or the clothes they will be performing in... some do... until their dry-cleaning bill climbs too high!

6. He shows respect and courtesy to the guests to whom he performs.

There is more, but the above
are the main characteristics.

This is only learned through experience!
I mean several hundreds of gigs in many
different contexts.