Pretty much wrong on almost all accounts.
- Graphic Design - To make even a little money with graphic design, you need to be really, really good. Courses will only help you a little. If you are THAT good, you can already make it a full time job. (it's also practically impossible to make this part-time. It can take 10 hours to design a single flier, and everybody needs it done "yesterday")
- Photography - Like our expert, SF said, in your dreams. For the record, "hobby photography" is a far cry from business photography. Business photography requires a LOT of equipment and hired help. It also requires actually doing a good job and not having people upset with the shots you took and then refusing to pay. Every other person I know has a side photography business on Facebook. Non of them actually make any significant money, even for a side job.
- Shadchan - Almost everyone tries their hand at this and some point or another, and quits after their first try. Shadchonus is murder, and you need to be able to sustain a lot of abuse. It also requires tremendous Mazel. How many people do you know that are actually making even a side job out of this??
- Grant Writing - How many clients are you going to get for this? one a year?
- Mileage brokering - I don't disagree, but have fun while it lasts. Airlines are already shutting accounts down right and left, Amex stopped online transfers, Chase is cracking down and will probably get tougher soon, SPG are rare and will probably crack down eventually.
If you are looking for side-income, you'll do better getting a real job that pays by the hour. The above-mentioned work is better as full-time.
Remember I mentioned these as part time supplemental income.
Graphic Design - With a little understanding of design you can design cards and other stuff for you friends and family, for example $25 for a email invite design, usually it is very simple. Flyer for your schools and shuls, logos (outsource it to those logo sites and no one will be the wiser). It is not too hard to earn 1k a month doing these small stuff
Photography - It is not about the equipment, it is about the photographer, if you have a little talent you can do just fine taking photos for those you know, eventually your portfolio will grow. Taking pictures at a bris / upsherin etc. for a low fee. Pro photographers will shred the pictures because white balance is off or it is too green.. But for the regular layman any high res properly framed picture with decent lighting will do just fine. Run it through lightroom and you will be considered a pro by them.
Shadchan - if it is something up your alley and your personality there is no reason it should not work. Look at it as a sales job. Some shadchanim charge a small fee just to handle your case, you do not need to do that in the beginning, you just need to be very devoted and pushy.
Grant Writing - I happen to know of many organizations looking for help with grants. Once you do one application and you learn the style, they will all be easier. I say this from experience.
Mileage brokering- Again, it has to suit your style, but the mileage business is not going anywhere, as the risk goes up so does the prices.
I forgot to add another easy option:
Real estate agent - The course is not that hard, nor expensive. You can easily join a large real estate firm and take advantage of their services (but you will need to give them a cut of your commissions). You will have access to your local MLS, you can either then advertise to the Jewish community, or you can just post those listings on Craigslist. You will get results. Baduk umenuash. The real money is in sales, especially if you are the listing agent (i.e. you are the one listing the house) but rentals can also bring in a nice side income.