Some of these tips are from big wall expert Mark Hudon. See more tips and El Cap route photos at his website and Instagram.

See related post - Assorted "vertical camping" tips

Here's another excellent page with some diagrams for setting up your ledge. One of several examples is below.

Give yourself enough room to set up your ledge, but stay secure. You need to move around a lot when you're setting up your ledge. To give yourself enough slack to do this, take a large bight of lead rope, tie it to the same anchor bolt as your ledge, and attach yourself to this rope with a GriGri.
Between using aid ladders and this extra rope, you should have enough room to swing around and set up your ledge. Because you are clipped into a closed loop, there's no way you can slide off the end.

It's pretty much a one person job. Setting up the ledge is generally best done by one person. While you're setting up the ledge, your partner can be unpacking the haul bags, sorting the rack for the next day, and stacking the ropes in rope bags.

Keep suspension straps long. The suspension straps are not really for setting the height of your ledge. They’re more for fine-tuning and balancing.  For the most part, they should be kept long and extended. If you shorten them up, they merely reduce the living space in your ledge.

Pay attention to the door on your rain fly, and make sure it faces your haul bags. For example, if your rain fly door opens to the left, you want to hang your ledge on the right side of the anchor, and have your haul bags docked on the left side of the anchor. This offers easier access to the bags once you're zipped inside your rain fly.

When tightening the floor tensioner straps, clip a carabiner to the straps, and pull on the carabiner to tighten up the floor. The carabiner gives you an ergonomic handle to really crank down on the tension straps, which is much easier on your tired wall hands. Tension the outside corners first, then the inside straps.

Hang from a fifi hook or adjustable daisy when leveling the ledge. The last step is to adjust the long straps that hang from the anchor point to make the ledge hang level. Fine-tuning this can be tricky to do when you’re actually standing or sitting on the ledge, as your body weight is constantly shifting the natural "angle of the dangle" of your ledge. Try this simple trick: First, loosen all leveling straps to their full length. Then, hang by your fifi hook or adjustable daisy from the anchor point of the ledge, putting no body weight on the ledge itself, while you adjust the length to make it (more or less) level. This lets the ledge hang in its natural position, but with you close enough to the corners so you can reach all the straps.

Attach a Yates adjustable daisy to the top clip in point of your portaledge. This gives you an easy way to adjust the exact height. Generally, this ideal position is about 2/3 of the way up the side of your haul bag. (Of course, this varies depending on the belay and bolt configuration.) This allows you to stand up in your ledge and easily rummage around in your bag. Adjustable daisies should be retired from lead climbing once they start to get fuzzy and worn out, and a “retired” daisy works fine for this ledge connection.

This Yates adjustable daisy is not the only connection of the portaledge to the anchor. Do you really want to be sleeping hanging off only some flat webbing in a cam buckle? I didn't think so. Mark’s pro tip: permanently tie 10 feet or so of 8 mm cord to the top of your ledge, and then have that go off to another bolt to back up the adjustable daisy.

Once the ledge is set up, transfer everything you need for the night to stay comfy from the haul bags. Ideally, you do this once, because getting in and out of the bags multiple times is a hassle.
Have your gear in color-coded stuff sacks. Mark likes different color coded bags: kitchen, food, clothing, personal care, and technology. This makes pulling out exactly what you need from the bottom of the haul bag a lot easier. You can get some sweet big wall stuff sacks from High Mountain Gear.

Consider hanging an aid ladder close to your end of the ledge. You can use the steps to clip in most all of your personal gear, and not have it dangle in your face when you're sleeping.

Having some sewn tie in points points added onto your ledge makes it much easier to keep your stuff safe and secure. Learn how to use a Speedy Stitcher awl to make your own, or make friends with your local shoe repair shop, who probably has a sewing machine that's older than you are that's sturdy enough to sew through heavy duty webbing.

Consider getting a dozen or so small “bivy carabiners” that are only used for clipping stuff bags, shoes, water bottle, etc. onto your ledge. It's helpful if these carabiners are all one model and color, so can tell at a glance they’re for camping, not climbing. In case you ever mix them up, be sure and buy proper rated climbing carabiners and not the cheapo keychain carabiners from the hardware store.

When you have it all dialed, you’ll be a happy vertical camper, like this guy!