One thing that you have to be really careful about is whether the photo-hosting site you choose allows hot-linking. That is, if you wish to have your images appear in a post. It can take some intense reading and searching on some sites to discover this limitation.
If you just want to give a link to where you have your photos stored, then you need to be sure that you have the gallery set as "public", such as for Facebook.
Another thing to remember when posting to AA is that you generally will not need to put the img tags around the photo(s).
The other biggie: select "Preview" to see how the photos in your post will appear. If things aren't quite what you want, then select "Edit". Once you're happy with everything, and your text and photos are perfect, then click "Respond!".
In addition to checking the size of your photos, and the text that goes with them, this becomes important when you're copying and pasting the same text / photos to different forums. Different forums have different coding, so while you might need an <img> tag in one place might need an [img] somewhere else.
This all sounds way more complicated than it really is....honestly. Once you do it for a couple of photos, you'll get the hang of it pretty quickly.
Oh, yeah...we use Paintshop to resize our photos. Well, once it's re-installed on the computer we will....yesssss, we had another computer "malfunction".
Barbara