There are a variety of different backgrounds as witnesses.

Some are highly technical, e.g. @smooth, @abit, @gtg, myself etc. - those with history in development and system administration are more likely to be trusted by the other witness whales. A vote from @abit for example, could throw you up 10-20 ranks if you're low down, or 5-10 ranks if you're in the top 50.

Some people like @charlieshrem never even operated his own witness, he paid someone else to manage it, and he was #1 witness for a while. This shows even without a developer/sysadmin background, you can still make it to the top 20 if you know the right people.

A large part of your success as a witness depends on how much the community likes you. If you're well known and liked by the developers, the whales, and the normal users, then you're bound to have great success as a witness.

Sometimes, even if you're practically a famous Steemian, you'll still be stuck at a low rank. Example: @teamsteem is one of the most well known and loved Steemians, with posts constantly breaching $1000, and yet he's struggling to make it into the top 50 after running for months.

The only way to find out is to try it. Setup costs for a witness are low, and you can always stop if it's not working out for you.