Hiring a professional art handler/installer is a smart decision if you want your artwork to look its best. I work with a crew that I hand pick depending on the amount of artwork to be hung, the size, medium, etc.

Installing artwork for best effect requires close consultation with the client, the art collection specs, the location for installation, and an art handler.

My many years of experience as an art consultant allows me to respond quickly to an artwork and a location and make decisions about the hanging hardware. I then communicate my directions to my framer to prepare the work for install. My framer may have suggestions and I am open to their ideas. For many years, I preferred to hang artwork off D-ring and picture hooks. This gives a very precise presentation. The artwork does not tip forward and there is minimal shadow around the picture. The D-rings do need to be inset from the edge of the frame so the picture looks like its floating when you view the profile. I will continue this practice when appropriate but I have been experimenting with hanging from picture wires and letting the artwork tip forward. It's a style-thing that is a work in progress. Hanging artwork has trends and important changes just like fashion and architecture.

But in regard to wire hanging - if that is what your picture has on the back do try to hang it on 2 hooks not one. The two hooks should be level and just a few inches away from one another. Hanging on one hook will only cause you distress in the long run. Any movement on the wall or near the wall can cause the picture to become crooked. And it is not easy to keep a one hook wonder level on the wall. You will be forever futzing with it.

There are so many techniques and special hardware that is available to hang artwork for maximum effect. It's impossible to put years of experience down here. Hire a professional art installer when in doubt. You'll be so much happier with your artwork and there will absolutely not be a lot of holes in the wall.

My mother in law hired a professional art installer for her paintings. She just has too many; had sold some when she downsized but still, she didn't feel confident to ask us to hang them or do the job herself. She also explained to me that she wanted a professional to help her group, arrange and 'distribute' the paintings around in rooms and hallways, not only by theme or artist, but considering colour, frames, size etc.
I think the guy's done a great job (just look at her entrance hall and 'music station' below) but, sorry, it never crossed my mind to ask if he used nails or something else. I use classic picture hooks for our place.

A timely question since I am going to be hanging my art once I finish painting my walls at the new place. I remember when I moved to California someone recommended using two wires and hooking each wire separately as a redundant system to prevent earthquake damage to my framed art. It also did a great job of preventing them from shifting and having to straighten them all the time. I think it may have been my State Farm agent who suggested it.

I do Not recommend Command products for art work.
I arranged a bunch of command hooks on the back of a door. The hooks holding heavy leather purses stayed on the wall, but one of the hooks holding a lite baseball cap has fallen off many times. I cleaned & dried the door before sticking the hooks on & bought the larger heavier weight hooks.
Don't trust sticky wall products to hold up art work. You don't want torn up canvas, busted frame & shattered glass!

Here's a picture of the back of a command package.
Read the caution! It states DO NOT use for antiques, heirlooms or other valuable or irreplaceable items. DO NOT hang items over bed.

These products are good for whatever you have that isn't precious & won't break or cause an injury if it were to fall. Stuff like laundry room, closet & pantry.

A better picture

I found command hooks with Velcro holds much much better. I use nails but I do use command hooks to straighten/keep corners straight--is my wall crooked?!! I also use wire and the hook. It depends how heavy the piece is. But I do not use just one method.

I collect vintage convex silhouette pictures. They are usually 4x5 and lightweight. I use straight pins at an angle to hang them on my sheetrock walls. Leaves no noticeable holes when I need to rearrange them. I prefer the pins that have the small round metal heads like men's shirts are packed with.

My mother was a graduate of art school with an emphasis on interior design and an art collector. She always hung my sister's and my art even though we didn't live in the same city. I learned my skills from her always using picture hooks and various measuring rules, but I agree large paintings need two hooks. I used to be recruited in college to put up everyone's posters on their dorm walls. I still go nuts if I see a painting too high or low. My decorator friends hung my set of small prints and it looks fabulous and I think they are still the best at this. We are about to do a major remodel of our house with a total interior paint job and I'm getting my designer to hang the pictures. It's worth it as we have so many. Yes, we inherited the parents' collection and have our own, too, sigh. I love Command hooks but I use them for dishtowels and bathrobes.

P.S. And I have plaster walls! The new addition will be wallboard, much easier to put those nails into.

Try living in Europe! Nothing short of a jackhammer drill and plugs are a necessity. I use the above with a Bosch grid line I project onto the wall to place the pictureOr I use art gallery systems with fisher mans line or cable from the ceilingBlue tack stick some thingsAll ranges of peel on stickers depending on the weight of the itemActual hooks for other itemsBasically a pandora box of tricks depending on the item...

I usually just use finishing nails, hammered in at a 45 degree angle. I even have a few large (40"+) stretched canvases held up with 2 finishing nails each. I've done this in plaster and drywall with good results and the holes are super easy to fill in when you take them out of the wall. Nothing has ever fallen of the walls, but I probably wouldn't use them to hang something sentimental just in case. For really heavy stuff, I use butterfly anchors. I always had issues with the molly style anchors just spinning in the wall when I try to screw in the screw, so I don't bother with them anymore.

I hate Molly bolts, and since a framer recommended, we've hung large artwork with two hooks. Works like a dream.

I use Command velcro strips for hanging everything. Some will hold up to 16 lbs. and they don't damage the wall.

Guess I'm old fashioned. I use small nails for lightweight framed art placed at a 45 degree angle. For larger prints, I use two bulldogs to distribute the weight. Always a good idea to check the condition of the wire before hanging. Command hooks are ok, but I dislike the space they take up which causes the item to hang top heavy. They're good for tea towels and such though.

Anchor Wire Gorilla Hook Picture Hanger
Available wherever hardware is sold. A very small hole and 50 lb working load.

I use T-pins bought in a craft store. They are strong and only put a very small hole in wall.

If the painting or object isn't too heavy I like to use straight pins. Hammer them in at about a 30 degree angle and only leave about 1/3 of the pin exposed. This works so well and there are no nail holes to worry about if you need to adjust

I used pins for my artwork since it is a light piece and can easily be moved in case I'd like to change the shape. Works really well so far.

we use magnetacks in our office and at home. they are magnetic tacks that hang posters and photos without damaging them. they are really strong and look pretty cool. magnetacks website

I have a small art gallery. I often use picture frame hangers. The frames are of different weight heavy frames are hung with strong clips or hooks while lite frames can be hung with help of small clips only. I think a picture hanging kit is good for all kinds of frames and other hangable.