Constructing a newsletter will always be a bit of a manual task, because there are as many "newsletter" options as there are owners of a zenstore.
The way I do it is to use a dual screen (though you can split one screen) and have my browser pointing at my store on screen1, and a html editor open on the other screen.
I call up new products in my store (screen 1), then highlight/copy their zencart URL in the browser address bar, and then paste/create a link (either behind a bit of text or an image) in my newsletter html.
As my product codes (model numbers) are the same as my image names, I draw the path to the image simply by putting the model number .jpg . (This saves time, as I don't have to go trawling round the image file for the relevant image name to put into my <img src> tag).
When I've completed the layout of my newsletter, I COPY the html code between the <body> and </body> tags, and paste this into my htmlArea window for newsletters.
I also tend to have several TEMPLATES (designs) for newsletters, so all I have to do each month is replace the images names in the <img src> lines, and the <a href> to the product info. (And the general text of course)