I have been stringing my own tennis rackets since 2000. I was fed up with some questionable stringing jobs from stringers in Singapore. When one "reputable" stringer broke my beloved racket at the time - a vintage Dunlop Max 200g, I decided to invest in my own machine.
Now the machine I bought isnt one of those fancy electronic types that tensions the string for you using a motor. I bought a manual Gamma spring tension machine instead. I have been using it for all this while and it hasnt given any problems. Made in USA does stand for something.
I am not a pro-stringer by any means but after stringing hundreds of rackets for myself and my friends, I feel that I at least can give some advice to budding stringers or people who want to get into stringing.
Firstly, buy a machine and learn how to use it. I would suggest that you buy a machine that will last you for some time, at least as long as you retain your interest in tennis. For me, manual is better - either a drop weight model (around 200-400USD) or better still - a spring tension model (around 700-1500USD). Get a model that has 6 mounting points. The electronic models are great but pricey and have the potential to break. Motors do break. Although stringing saves money in the long run, you have to string lots of rackets to make up the cost of the machine. I estimate about 6-12 dollars saved per racket strung depending on the string that you choose. My Gamma cost me about 800USD incl shipping and I think it has only made up the cost in the last few years (I typically do around 20-30 string jobs a year). There are plenty of guides to stringing out there and YouTube has plenty of videos as well. In addition to the machine, you will also need a sturdy table or stand (stands are usually additional), some cutters (standard wire cutters will do), a pair of pliers (I use the bent nose ones), an awl (to act as a pathfinder for new holes) and lastly a measuring tape (I tape the tape to my table).
Types of string and stringing methods. In addition to the machine, you need to buy string. Hopefully by now you would know a little bit what types of of string you like - what thickness or "gauge" you prefer. There are literally hundreds of string out there, and they come in single pack or in reel form. For the sake of economy, I usually buy reels of string. As a rough guide, I usually stock a big reel (600-700feet) of a good and cheap synthetic - for me I use Gosen OG Sheep Micro 16g or 17g. Gamma and Prince make great synthetics as well. I also have a reel or two of polyester string - I currently alternate between something by Luxilon or Topspin. For the last few years, most of my stringing jobs have been using the 2 string method and I have been doing hybrid stringing jobs with poly mains and synthetic crosses. My current Wilson rackets are mostly strung with Topspin Cyber Flash 17 on the mains and using a synthetic like Gosen OG Sheep Micro 16g or Gamma Synthetic 16g on the crosses. I use a thicker gauge cross as the synthetic cross will usually break before the polyester main. Stringing using the 2 string method has several benefits - the stringing jobs typically take less time and there is also a little bit less wastage compared to the 1 string method. I usually dont do any fancy patterns "Round the world" or no shared holes. For maximum economy, I usually measure and cut the optimal lengths to string a particular racket e.g. my Wilson 85-90 sq inch rackets typically only require 18ft for the mains and 16ft for the crosses. I usually take 35-40 minutes to do a single racket (a tip - dont be too fixated about speed when you first start).
Maintenance. My Gamma has largely been maintenance free. The only thing I do once in a while is to use a tension calibrator to make sure that the tension is correct and do a rough wipe down.
Has stringing my own racket helped me in my game? Well to be honest, not really. Putting the best stuff on your racket wont make you the next Federer. Some times I get the urge to just throw my racket at a stringer and get it done. You get the convenience of stringing anytime you want or whenever you break string. For me, I save some time by not having to travel to the stringer location and make another repeat trip to collect the strung racket.
Does it make sense to have your own stringing machine if you only have one racket and you only play once a month? No. I would say that you should only do this if you play frequently (about 1-2 a week minimum) and you break string often. The general advice is that you should restring your racket annually as often as you play a week e.g. if you play once a week you should restring once a year.
Let me know if you have questions and I'll try to help!