If you want a fun time and you don't want to worry about selling or making goods, play a Thief.
Kidnapping works best when your target has a low combat statistic and TONS OF MONEY. The lower the combat stat, the easier they are to capture and the amount of money they have makes the ransom you receive higher.
Once you have the maximum number of employees, use them wisely. For example, have a couple scout some houses and a couple in training. A well-trained thief is a valuable thief. Once the ones in training are done send another batch in for training until you have their stats maxed out.
When playing a Thief: make sure to scout any potential places that you are going to rob until you have 96-100% information on them. Also, just before you send out your thief to rob the house in question you will be looking at an over head view mini-map. If you see any dots (people) walking around the location, wait until they go away and then send your thief out to rob the house.
Make sure to work on your primary stats (Stealth for a Thief, obviously :D) because your stats make for better thieves.
Also, feel free to ask me (or TheJoe or Drlstvaan) any questions as we are always glad to help a fellow Guild player.

Thanks for the tips JudasIscariot. I won't hesitate to PM you if I have any furhter questions
I'm looking forward to play it as soon as I have some spare time.
So many games to play and so little time...

No PMs on the forum, sadly.
email me at slyscorpion (małpa) gmail.com if you have some questions.

Oh, crap. I haven't noticed it before. Thanks again.