This was a big change for me initially. I spent the summers from the age of 15 until I graduated from college as a lifeguard and swim instructor, so I wore a bathing suit pretty much all day, every day and I was thrilled when I moved to a college pool and could wear a two piece. So the first big challenge is usually my bathing suit. I love to swim. I don't love bathing suit shopping.
In the past few years I've worn various practical one pieces and a maternity two piece where the loose top flows down over the bottom. This year I discovered swim dresses and was actually quite pleased with what I found. They look something like this, although I can't find the site I bought mine from now, where the suits were much less expensive. I wouldn't wear a swim dress out walking down the street, but it will be fine from my dash from the pool to my towel.
The skirt and dress issue doesn't really pose a problem during summer. Long skirts and dresses made of lightweight, breathable material (like cotton) can really be quite comfortable. And after wearing a skirt for quite a while, I've learned that I really can do pretty much anything in my skirts that I could do in pants.
My personal standards for my skirts and tops have come from that tiny feeling of discomfort I get when I feel something isn't modest when I'm wearing it. If I find myself tugging a skirt down or a top up, then, despite the fact that it's probably 10x longer than the norm in our culture, I've got to make a change. I've finally begun to discover the lengths at which this happens and here are my own personal (for me) standards when I search for clothing.
Skirts and Dresses: Must be knee length of longer. If they are right around knee length they must be loose enough that they aren't going to hike up to mid thigh when I sit down but still cover to the knee (oh I discovered that the hard way).
Tops and Dress Tops: No cleavage whatsoever. If a dress is strapless or has spaghetti straps, than it's going to be paired with a sweater, even in summer (although their are some cute short sleeved sweaters now). But (and this is where it becomes difficult) it also can't be impossible to nurse in (or even particularly time consuming to be able to nurse in). Thus I sometimes pair thin or no straps with a sweater, to facilitate nursing while remaining modest.
Shoulders: I struggle with this the most. I have wide shoulders for a woman. It can be hard to find shirts that look right. Thus for me, strapless or spaghetti straps were pretty much the way to go, back before I started thinking about these things. Now it's still a battle to find tops that fit correctly and that aren't tight on my kind-of-strong-at-the-moment-baby-lifting-arms (who knew lifting a 40-something lb toddler and a 20-something lb baby would be such a great workout!). Usually I go with a sweater to solve the issue. But I'll admit I struggle with this every single year!
I know that these vary widely from woman to woman, but I thought I'd share what I've come up with for me! Do you have standards that you hold yourself to? If you do how did you come up with them?