It's no wonder some of our ancestors are so difficult to find. If I would have known that Asa Brown's name in the 1850 census would be indexed as Asa Prowse (Ancestry's index) or Asa Preuss (FamilySearch's index) he would have been easy to find. To have greatest success in finding our indexed ancestors, we must think like indexers.
Here are a couple of tips that have been helpful in my research.
Tip 1 - Years ago, before anything was online, I found this family living in Neshannock, Lawrence County, Pennsylvania. Because of how they were indexed, it was difficult finding this record in any online database. I eventually located them by searching for just the given name of one of their children. I searched for William because I figured most indexers can decipher that name. I combined the given name with his age of 9 and added Lawrence County to the search parameters. Try different combinations.
Tip 2 - Correct the index if you can. If you're using the Ancestry index, when you are looking at the actual image, click on the View All link in the upper left. This should split the screen, showing you the indexed entries. Then, hover your mouse in the far lower right (just above the View Updates button) and click on the Add Update button. Here you can add alternate names, which will then be included in the index so future researchers can more easily locate the same person.
Tip 3 - Do some indexing. Through my indexing efforts I've become a better researcher. It helps me think like an indexer. Now when I see a "J" I know that it can easily be interpreted as an "I". An "L" and an "S" are nearly identical as well. In fact, in Kip Sperry's Reading Early American Handwriting, he explains potential problems and solutions with every letter of the alphabet. Here's his example for the letter F:
Two small ff(s) were used to form a modern capital F. A small f or backward lower case f may look like an s. A capital F may be confused with a capital H.
If you are not yet familiar with the long s you can easily mistake it for an f as is the case with the name of this township in the 1840 census:
Many compiled records have published this name as "Scrubgrafs" when it should be Scrubgrass. My semester-long paleography class as part of my genealogy degree was well worth it. At the beginning of the class I could not read anything our professor presented, but by the end, with the tips and techniques I learned from Kip Sperry, I could easily read the same documents. I strongly recommend that you read his book.
Tip 4 - Be creative! Try to think like the indexer and the enumerator. I don't think the enumerator double-checked that his spelling was correct for every name in the household. Try to think of all the surname variants and spellings. When you've exhausted your own creativity, use the three online tools I wrote about in Three Free Resources to Find Surname Variations.
Tip 5 - Use Legacy's Soundex tool. In Legacy, go to Tools > Soundex Calculator. Fill in the surname and click on the Search Name List button. This will give you a list of all surnames that share the same soundex code, so you might locate other variations of the same name.
Have you located someone in an online index where the name was terribly transcribed? What techniques did you use to locate your ancestor?