There are several ways to make the search so that your chances of finding the person you are looking for are better.
The main thing is to remember that the name was often spelled in different ways. So do not go for the exact spelling as a first choice. I have personally had people that had their name spelled in 4-5 different ways through out their life. And many times that the person had two names and depending on the different circumstances one or the other was left out.
So look for what is certain to be present in the name and start there. If for instance our ancestor was named Kristoffer Kristoffersen and the source of that name was the immigration papers. Then do NOT take it for granted that that was they way he spelled it in Norway.
So how do we crack that nut? Though something called "wild cards" And Digitalarkivet have several of them.
|Wildcards||Action||Example||Gives hit on|
|?||This replaces any character.||Ann?||Anna, Anne and Annie and like|
|*||This replaces none, one or several.||*ristoffer||Christoffer, Kristoffer and Ole Christoffer, but not Christopher|
|The letter may be there but doesn't have to||Pe[e]r||Per and Peer|
|[a,å]||One of the letters have to be there||Krist[o,å]*||Kristoffer, Kriståffer, Kristopher and so on.|
|%||to be placed in front of search word. The system puts in suitable [ ] and drops vowels||%agt||All variable of agate like agate, agåte and so on. The search takes awhile.|
|-||To be used in between||1881-1900 d-f||All the years between 1881-1900. evrything that begins with d to f|
You may also find some help at Digitalarkivet at: http://digitalarkivet.uib.no/sab/howto.html