Be VERY good and be a little lucky.
Many title companies in urban areas already have a relationship with signing services and it is very easy for them to order a basic signing agent from one of those signing services. If you are only as good as a basic signing agent then there is little to no motivation for them to use you (but of course it still doesn't hurt to market yourself).
HOWEVER, if you are an above average signing agent who understands how to make life easier for the escrow officer / escrow assistant then they have a reason to choose you first. Examples of making life easier for them is knowing how to fit seamlessly into their office so you don't look / sound like a signing agent but you look / sound like you belong there. Knowing how deal with realtors (who can sometimes be a pain in the hiney in my opinion). Knowing how to pull certain documents that the escrow officer or assistant may need (for example, if you are doing the buyer part of the signing pull out all of the documents that the seller needs to sign so they won't waste time doing it). Knowing how to spot potential issues and bring them to the attention of the escrow officer / assistant. Etc.
I am personally not a big fan of walking into title offices during working hours - I find that they tend to be busy and not happy about interruptions. Instead, I would suggest going to meetings and marketing events where title company employees will be in attendance. Your local board of realtors probably holds monthly marketing meetings, people are there specifically for the purpose of "meeting and greeting" others in the industry.