I tried the whole setup buy orders all over the place, and it was more of a pain than it was worth to be honest. I will sometimes setup buy orders in Jita or wherever I am selling, but asside from that, I have given up on them as I would spend hours just simply picking up all the gear to move it. Yeah the profits were higher, but the amount of time I had to invest was not worth the extra profit.
As for items, well, you really need to simply look at the market. About the only thing I don't sell are ships, rigs, and minerals. Anything else is fair game for me, it just depends on what the markets are saying. I will say stick to items players can't make in the beginning. The item drop rates are pretty well stable, and it is rare to see someone horde those items and dump them on the market (since they lose out as well since it drives the price down). Things that players can make, on the other hand, can easily get flooded on the market. People dump thousands of things in the different regions which the region has no capability to use the supply all the time, especially for ore and rigs. Heck, it would only take 5 people making certain rigs for a week to out-produce the yearly demand for those rigs across the entire game (let alone a region), and that happens all the time with new players coming in, buying their first blueprint and starting to mass produce something.