Tips on how to run a PC with a small SSD
Installing a Solid State Drive can be an excellent addition to your PC, however, the new era of hard drives comes with a hefty price tag. Things aren't quite as bad as they used to be, but when you start talking about Terabytes, SSDs quickly reach the $500+ range. Luckily, there's a lot of different SSD sizes to choose from, you can snag a 120GB for just under 100 bucks, and a 250GB for about $160. Obviously this isn't a lot of space -- but there's some steps you can take to make life a little easier, even with a small SSD.
Keep Your Old Drive Installed, Or Purchase an External HDD
If you've already got a PC, and you're just looking to upgrade the HDD to a SSD, you can still leave the old drive in your computer if there's enough slots. You'll want to make sure that you run your Operating System off of the SSD, otherwise you're pretty much just wasting money, but you can still store files on your old drive. Keep your programs and OS on the SSD, but move things like documents, pictures, videos, etc, to your HDD -- there's really not much benefit to having these on an SSD.
For those building a new PC, or using a Laptop that may only have one Hard Drive slot, you can purchase a USB External Hard Drive. You can get a 1TB External drive for around $60, and it could be well worth it to drop a few GB on your SSD in order to buy a big external HDD.
Remove Space Wasting Temp Files Regularly
Windows periodically puts some large temp files on your computer, and you'd be surprised at how much space these can occupy. Since we're desperately trying to save space here, temporary files should be the first thing to go, so check this before you start getting rid of programs. Most of this can be done manually, but you don't need to, instead download CCLeaner and run that. Usually you can just remove anything on the list, some advanced users may prefer to leave certain areas intact.
If you haven't cleaned up your drive in a few months, or ever, you could see several GB free'd up just by doing a quick CCleaner scan. The software is free to use (a pro version is also available), and I've found it to be invaluable.
Consider Switching to a Smaller Operating System
Even if storing personal data elsewhere and getting rid of temp files wasn't enough, there's still a couple more options you can consider. There's a lot of different Operating Systems that take up less than a GB of your hard drive, which is a huge difference compared to the ~20GB you'll use with Windows 7/8. You give up a lot of compatibility by doing this, but it's something to consider if you're all out of other options.
Some quick links for you to look at: Kolibri (Only uses 3MB!), Ubuntu (very popular, great choice). and Damn Small Linux.
If All Else Fails... Compromise with a Hybrid!
Switching your OS may be out of the question, so if the other options don't quite cut it for you, there's some Hybrid SSD/HDD alternatives. These are tremendously cheaper than buying a regular SSD, and are way faster than a standard HDD. You can find a 500GB Hybrid Drive for around $75, and a 1TB for $100. These prices aren't much higher than a regular HDD, which leads me to believe that standard HDDs will soon become obsolete.
Essentially, these drives have a small amount of SSD storage, and the drive uses "Adaptive Memory" to figure out which files the user accesses the most, and moves them to the SSD memory. You'll experience boot speeds just slightly slower than an SSD, but a whole lot faster than a HDD.
These tips should be enough to save at least a few GB, but if even after all of that, it still isn't enough, you may just need to fork over some more cash or compromise on some other specs of your computer.