As a poor student when I did most of my home printing, I learned from school what I "needed" and what I did not.
+ A lot of household stuff could be used for photo use; measuring cups, buckets, clothes pins, tubs, trays, etc. Although today, you can find old photo gear so cheap or free, that the household stuff is expensive in comparison.
+ In high school and college, I always carried a pocket knife with a cap opener. Always had it with me when the "official" 35mm cassette opener went missing...again. Probably could not get away with carrying a knife in school today.
+ One of my best tools is a small Cds enlarging meter. When I had to repeat print or adjust the enlarger height, it was easy to get a good or close 1st print. This was important as I did not print enough to develop my eye to be able to judge the exposure of a negative. The meter also gave me a better evaluation of the brightness range of the negative, for the same problem of not enough darkroom time for my eyes to judge.
+ An inexpensive alternative for a close first print is the Kodak Projection Print Scale. I think it was 60 seconds and you read the exposure time off the pie slice with the best exposure. Much better than the traditional test strips, which in later year I realized has a problem. Standard test strips (increments of 2 or 5 secs) were linear, not exponential (f-stop). So the exposure increments were not even as the exposure time increased; 4sec was 2x 2sec, but 10sec was not 2x 8sec, it was only 1/4 more. I tried to do an f-stop test strip a few times but it was hard to get the incremental times correct, and I gave up trying.
+ RC paper to avoid the hassles of drying fiber paper at home.
+ Honeywell Nikor developing tanks were/are great, and has lasted me well over 40 years. And they work just as well today as they did back then. They use less chemicals than a plastic tank, and it was easy to clean, wipe and immediately use again (plastic reels were a PiA to dry enough to reuse them in the same developing session).
+ GraLab 300 timer. It was an expensive purchase for a high school kid, but over the long haul it worked out better than the cheap plastic timers that always broke and the wind up kitchen timers were difficult to set to anything less than a minute so their accuracy was no better than about 1 min. I also used the GraLab as my enlarger timer until I could afford to get an enlarger timer. So I used it for many timing purposes. The only real use of the kitchen timer was timing the 10 minute fix and the wash where accuracy was not important. Today there are many inexpensive digital timers.
+ In the local community college I saw what bdial mentioned. A LARGE clock with a safelight on it, EASY to see the second hand. With several people developing prints at once, it wasn't practical to have individual developing timers. And you don't have to touch the clock like I had to do with my GraLab. Or put my wristwatch under the enlarger with the light on, to see the time.
+ Honeywell RotoTrim paper cutter. I HATED using the standard giloutine paper cutters in the darkroom at school. Blasted thing was dangerous to use in the dark, and you ALWAYS had to make sure that the guys before you did not leave the blade in the UP position. The RotoTrim while expensive was a heck of a lot safer for my fingers in the dark. There are much cheaper basic rotary cutters today, so a rotary cutter should be an early purchase.
+ Durst M600 enlarger. It was an awful $ stretch to buy it, but it worked well and long. The M600 was portable enough that I have dragged it from my parent's home to my apartment to house to apartment to house to house, for over 30 years. And it packs away in a relatively small box (for an enlarger). So if you don't have a permanent home with space for a large enlarger, get a portable enlarger.
+ Today with prices of used gear what they are, get the best enlarger you can afford, and make sure you have ALL the parts (missing parts can be EXPENSIVE to replace). In fact get a 4x5 enlarger if you can, as that will cover everything up to 4x5, so you won't have to look for another enlarger later. My M600 maxed out at 6x6, so I could not print any larger format film. I have a Durst L1000 (4x5 format) that will go into my new darkroom.
+ Making my home darkroom WHITE. I experienced the black-hole of a black darkroom in high school. It was difficult to work in, things got lost in the dark, it was easy to get hurt running into things you could not see (also black counters), and was just not a pleasant place to work in. Then I visited another high school where their darkroom was painted in pale green and white (no idea about the green paint), and it was SOOOO MUCH BRIGHTER, and easier on the eyes to work in. So, at home, 2 small 15w safelights lit up the entire darkroom; the white walls, white counter top and white tile floor bounced the safelight around so there were no dark corners. A couple of my friends could not believe how bright my darkroom was compared to the BLACK school darkroom, which had many more safelights.
+ Honeywell Nikor Rocking Print Tray. When I moved away from the darkroom my parent built, I was at times terribly space constrained. The rocking print tray let me develop prints in a small half bath. One could do similar with a drum processor.
- I wish my timers had a foot switch, but none had/have that option. I have had to use my elbow to trigger the timer while I dodged and burned a print, quite clumsy.
Maybe I can rig a connector to the switch and connect a foot switch to that.
- The worst investment (in retrospect) was my parents building a dedicated darkroom under the house for my brother and I. Although I think it had a lot to do with my mother wanting her kitchen not to smell like fixer and stop bath. After college I moved out and away. I don't think the darkroom was used much in the 30 years since. I hope to retire back to that house, and put it back into use.
- Cibachrome. I did not print enough slides to really have made that investment worth it. Although I was able to dodge/burn a few prints that could not have been made by a straight lab print. And unfortunately, Cibachrome is gone, or I might have played with that in my retirement.