The 10 million and under skill book market segment has been very good to me. I've made billions off it but I just pulled out (reluctantly) because it's the low end of my business now and my business has grown so much it became impossible to continue working this segment properly.
Over the last 3 days I've pulled out of the 10 million and under (school price) skill book market in Lonetrek region and 4 of the 5 main hubs (I'll be pulling out of the 5th soon too). Already buy prices are plummeting and sell prices skyrocketing.
Conditions are now perfect for new traders to set up in this market and make a lot of ISK.
In particular, right now would be a great time to set up in Lonetrek buying skillbooks under 10 million regionally. Full regional, 5, 10 or 20 jump buy orders will all work fine, just remember the larger your buying range the more work you'll have flying around picking them up.
Start out buying one or two of each and update prices at least once a day. As your capital builds up slowly increase your order sizes. Sell what you can on Sobeseki, Torrinos, Nonni or one of the many smaller hubs in the region and unload overstock on Jita (preferably on another alt there).
If you're short on ISK start out with just the books going for 5 million or less.
If you're a true newbie and really short on ISK, work the cheapest skill books first (under 1 million at schools) until you can move into the 1-10 mil market. High Speed Maneuvering (350k at schools) was one of my best items in my first weeks. I bought stacks of them for 75-150k and resold them for 350k+.
Best named modules (meta 4 for the most part) are great starter items for newbies too. Item's like Limited Adaptive Invulnerability Field, Local Hull Conversion Nanofibers and Eutectic Capicitor Rechargers. You can buy huge stacks of them cheaply in Lonetrek and move them to Jita for nice profits.
If you have plenty of ISK but are short on orders start out with books going for 5-10 million instead.
If you have plenty of both ISK and orders, start out using buy orders for 5, 10, 20 or more of each book. Obviously bigger orders for the cheaper books and smaller orders for the more expensive ones.
One of the best things about the skill book market is the vast majority of books are sold by schools which sets a soft cap on prices and prevents rich players from manipulating prices too much. Nobody can simply buy them all out and jack prices sky high. Even when margins are extremely tight, as long as you're paying less than school price and selling for more, you're golden.
You can make billions every month off this business alone. I did. The only drawback is it's fairly time intensive. It's great at first but the bigger you get the more time it takes.
Any book with the word "Specialization" in it trades well, "subsystems" and science books are pretty decent too. Some books do sell better than others and some sell a lot faster on a main hub than they will in Lonetrek but all books in the 1-10 million ISK range are good to trade. Weapon books (like those "specialization" books) and spaceship command books sell well just about anywhere.
The same strategy works in any empire region, I suggest Lonetrek because IMO it's the best place for a regional skill book business like this. There are plenty of customers around but the business is spread out on multiple secondary and small hubs all over the region, meaning no-lifers and bots are less of a problem than they are on the main hubs.
I almost forgot. Do not use a big, slow industrial ship for this type of business. The items aren't bulky, all you really need is a small fast T1 frigate. Fit it for speed and agility (nanofibers) and use Hyperspatial Velocity Optimizer rigs if you can. Mid slots you can either tank or use cap rechargers (very useful for low skills alts having trouble making warps all in one shot).
Even better if you can use a Covert Ops frigate or best of all a Blockade Runner, either of which makes low/null pickups a whole lot safer.
If you're in an NPC corp (no wardecs) and aren't a criminal you can autopilot most of the time as long as you realize you will get ganked eventually and lose a load. Be careful about using autopilot in 0.5 systems though, especially Litiura (assuming you're in Lonetrek) and never use autopilot in low or null.
Don't even bother passing through EC-P8R (null sec) or Aunenen (low sec), it can be done but it's just not worth the trouble. If you buy something in or behind those major gate camps it's a whole lot simpler to just put it up for resale at a good price (for the buyer) right where it is.
Lonetrek really is a great place to do business! More on that later.