I am contemplating putting A/C in my garage, but first want to insulate the garage doors and see how much that helps. The doors face west and get full sun all afternoon. Needless to say, the garage gets toasty! What's the best way to do it? Just buy one of those foam kits? Anything to look for in particular? I have a single door and two car door.

Make sure it does not add a bunch of weight. My last house had insulated garage doors with wood facings. I went through several openers and springs because the weight was hard on the equipment.

Measure everything - the pre-cut 'garage door insulation kits' will prolly be the best way to go. 1.25" thick, and will make a ton of difference on a west-facing door(s).

My doors are east facing, and shaded from noon on. but I put 1/2" thick Styrofoam pieces I got free from shipping cartons, and it made a heck of a difference.

Maybe consider something light weight like this...

Garage Door Insulation

I've seen those, but they seem gimmicky to me. Seems like actual insulation would be much more effective. Do you have any experience with them?

I bought some of that very light foam board from a building supply about 18 years ago, it was 1/2" thick. A few sheets do not weigh much. I just cut them to fit and popped them in. I can't say that I could really feel if the doors were significantly heavier, but I did notice a change in the heat coming through them, It has held up well. And I do not have an opener so I do not know if it would make a difference

Buy the 4x8' sheets of foam at HD or Lowes, cut them oversize and pop into door panels. I've done this on shop and garage doors works like a charm. Sheets are about $20.00 each.

How much do you guys think it helps to put the foam in the doors? My garage doors are metal with the foam inserts in the panels, and according to my temp gauge my garage was 93* when I got home today.

What is above you garage? Media room?

Mine faces east but I got insulated panels when I had doors put up years ago. Makes a difference in sound during operation more than anything. My doors are 8' aluminum with no windows so they are not heavy. The OEM insulation is 2" thick coated styrofoam.

Years ago on a 3 car garage door set up, used rolled fiberglass insulation and sprayed adhesive on door and pressed.. Worked for years until i sold place. Not overly heavy for door openers.

My door faces NW and has the silver insulation (HD) and I tinted the windows and it still get in the mid to high 90's in there. The attic space above it is the only place that has no insulation. Floor is covered in plywood for storage. Was going to pull up the plywood and put in insulation this year, but medical issues have that project delayed. Also thinking of a garage ceiling fan that dumps in the attic but they're expensive.

Also remember when you park a 6000lb hunk of 100 degree metal in your garage, it's going to heat-sink that place for hours. Insulation will hold that IN as well as it holds sunlight OUT. Routinely it's been 83-86 in my garage in Lubbock most of the summer at 7 am.

Metal Mart has a rolled foam insulation, I think it has about a 10 R value, but I don’t know why you couldn’t double it.
You could use spray adhesive or double stick tape to install.

The spray foam in a can makes great adhesive for styrofoam panels.

That's a great tip!

I’m gonna have to remember that.

I added a mini split to my shop and tried that stuff on my 2 garage doors (1 on both ends of garage)...I do not recommend it! After getting the doors all cleaned and oil free, nothing stuck very well and I was constantly having to re-stick this stuff in place. Ended up ripping it all down a week later and will be doing the Styrofoam inserts per my insulation guy when I get back home

Regardless of which insulation methos you choose, it's important that you also make sure to have good perimeter weatherstripping, otherwise a lot of what you add for insulation will not be as effective.

3/4" blue foam panels, excellent for insulating stuff like that.

glue on with a polyurethane adhesive, pl4000 is my favorite.

https://www.lowes.com/pd/GreenGuard-GreenGuard-LG-3-4-X4-X-8-XPS-Insulation-Board/5001939505

My garage just has attic above it. I had the rest of the attic foamed and closed to make a dead air space. It cut my electric bill by about 40%. Now I thought I would have the attic over the garage foamed. Well that didn’t work out to well. The foam works so well that the garage holds heat so good it is the same temp as the outside temp

I picked up some panels at Lowe’s this morning to do my shop door. I’ll knock it out sometime this weekend and take pictures with details. It’s a R5 value and the total bill was around $188 but my wife managed to add several plants to that. The insulated panels were about $85 plus tax. The door in question is 12x10’

I cut my insulation panels a little big and bowed them to pop them in. I never used any adhesive, they will not fall out.
For the kind of doors that I have this worked great.

I used the foam panel kits from Home Depot on our 2 double garage doors. No issues with weight. Been in for several years. My detached garage has a mini split and cools well. 12000 BTU in an over sized 2 car space. It is about 15 feet longer than a standard 2 car. Attic and walls are insulated and dry walls. The roof decking is foil barrier.