Causal is the most difficult of attire.  Easy to wear, hard to know what is right.

Casual varies by the setting.  You can have casual day at work, a casual party, or casual attire around the house.  Each of these outfits is probably something different, so choosing the right  look is not easy.

Basics

Let's start with some basics.  A gentleman wants to show honor and respect for others, including those with whom he has casual contact.  So, how should a gentleman demonstrate this?  As a lady friend once said to me, he should look nice, even when he's just "knocking around."  That would mean, to me, that my hair should be combed, teeth clean (of course), face shaven (although I will allow myself the leisure of not shaving on Saturday), and clothes in order.  By the way, I have a beard so not shaving on Saturday is a less noticeable issue.  If you look unclean with a day's growth of beard, then shave every day, even on Saturday.

Clothes in order would be clean and neat clothing, no holy pants here (rock stars can do that, the rest of us should not try to pull it off).  As I stated on the previous page, the shirt tail should be tucked in, unless it's a shirt that clearly does not belong tucked in.

Blue jeans are common casual attire among Southerners, and I frequently am seen in them.  However, we should be aware that among many people of other cultures, jeans are not seen in the same regard, so if meeting with anyone from north of the Mason Dixon line, or west of the Sabine River,  I consider whether the occasion might require slacks, instead of jeans.

For playing golf, or tennis, or other activities that are sports, yet social, consider that the finer country clubs in the country will not allow you on the course in a shirt without a collar.  T-shirts are just not appropriate for these types of settings.  Shorts are okay if they are the type you have typically seen in that venue.

There is no setting whatsoever where a shirt without sleeves is appropriate for a gentleman.  This is fine for wrestlers, bikers, or seven year olds, but not for a mature man.  Even if you're mowing your yard, this can look pretty disgusting.

Wear socks.  If you're wearing shorts, white socks are probably your best bet.

Wear shoes.  I'm a Cajun, and wearing shoes is a difficult concept for me to grasp, but I wear them.  Sometimes cowboy boots are appropriate, but consider the circumstance.  Tennis shoes, running shoes, or similar types are good for various sports or similar events, but never wear them to a casual party, or casual day at the office.  For these places a penny loafer or similar leather shoe works just great.

Hats or caps are just fine when you're outdoors.  But, take them off inside, and for love's sake, please never wear a hat while you're eating.  I live in Texas these days, and hear that a cowboy only takes his hat off for one thing, and it's not dining.  Well, that's fine for cowboys, but very wrong for a gentleman. 

By the way, on the subject of hats, if you ever want to see a lady smile, tip your hat when you greet her (outdoors, because you're not wearing it indoors, remember?)  I do this, and I know that they go home and tell their husbands and friends about the stranger on the sidewalk who tipped his hat.  I can see it in their smiles.

Rule of Thumb

My wife suggests as a rule of thumb, comfort with a little polish is appropriate casual.  Never be concerned about looking a little nicer than the rest of the crowd.  It reflects well on you, and your companions will, imperceptibly, recognize you as a confident individual.