Memory Card Reader
In addition to your larger capacity memory cards, you also might want to consider a memory card reader. This is a handy device to have, especially if you take a lot of pictures and are going to use more than one memory card. A card reader is a device that you attach to your Mac via a USB cable.
Then, once you have a card or two's worth of photos, you insert the cards into the reader to download the photos onto your Mac so you can see them, do any type of corrections to them using a program like Apple's own iPhoto or Adobe Photoshop Elements and then share them with your friends and family online or by printing.
Shoot Some Pictures
Next, you will want to actually use your new camera and take some pictures. Feel free to do what most people usually don't do and read through the manual that came with your camera. Believe it or not, many people actually learn a few things when reading the manual -- so don't be afraid and dive right in. Another option is to read one or more of the books geared towards those new to digital photography.
A couple good books to start with are Scott Kelby's Digital Photography Book or Understanding Exposure by Bryan Peterson. In addition, Apple, being the creative-minded company that it is, also offers a section on its website featuring tips for photographers using tools such as iPhoto and Aperture.
Regardless of whether you read the manual, one of the books above, or nothing at all, if it's your first time, it's okay to leave the camera in auto mode and snap away. Modern cameras are pretty smart and know more about things like exposure and color temperature than you or I will ever know. So, don't be ashamed to shoot with your camera in auto mode when starting off.
Organizing and Working With Your Photos
Now that you have your camera and are going to be taking lots of photos, how will you organize and work with them on your Mac? Fortunately, there are several tools that can help you accomplish this. For example, Apple's iPhoto is a great tool that's included with your Mac and helps you stay organized by displaying your photos in one convenient window. iPhoto also allows you to make adjustments to your photos including red eye removal, cropping and exposure.
In addition to iPhoto, Apple also offers a more advanced organization and image editing tool called Aperture. This program has most of the same features as iPhoto, but offers far more in the way of image editing and manipulation capability. Plus, it offers you a better way to work with RAW photos taken by some of the more advanced digital cameras like the Canon G10 or Nikon Coolpix P6000.
Adobe also offers a program similar to iPhoto, but with many extra features as well. This program, called Lightroom, helps you organize, tag and edit your photos and, like Aperture, caters more to the advanced amateur photographer with tools that not only help you get organized but also to make adjustment and crop your photos. There are, of course, other tools such as JAlbum, Stimulus or Microsoft's Expression Media, but if you're just starting out, iPhoto offers a great combination of features and ease of use. Plus, its already on your Mac.
Photo Printer or Online Photo Sharing
Finally, to allow your friends and family to enjoy your photos, you will probably want to print them out, or even better, post them online so they can all experience your photographic genius. There are several alternatives online to post your photos such as Fotki, Zoomr, Google's Picasa, Shutterfly and Apple's own MobileMe, but my favorite, and one of the most popular, is flickr. Flickr makes uploading and sharing your photos very easy and also offers a lot of other resources including lively discussion groups and a community of other photo enthusiasts.
You can create a free Flickr account at any time, but you're limited to the 200 most recent images in your photostream and 100MB in total uploads per month until/unless you upgrade to the $24.95US/year Premium (aka Pro) subscription. If you go Pro, your uploads, number of photos in your photostream, storage and amount of bandwidth are unlimited. Plus, you also gain the ability to upload video as well as stills.
For printing your photos at home, the major printer makers, including HP, Canon and Epson, all make printers devoted to printing your photos. Personally, I prefer Epson but many people also get good results from Canon or HP. If you do decide to get a photo printer, one important piece of advice: For best results, always use the printer paper made by the same company as your printer. Also, third-party ink, while sometimes less expensive, doesn't yield the same results as ink made by your printer manufacturer.
In the end, the important thing to remember when using a digital camera is to have fun. Take as many pictures as you want and as you go you'll soon discover what looks good and what doesn't. Modern technology allows you to indulge your creative whims. So, go out there and start shooting some pictures!