@Amanda Moore I'm not a wholesaler, however lead capture and follow up are pretty universal concepts.. so my question/suggestion to you would be this: I am assuming you are at least receiving some amount of phone calls from your marketing which tells you that you have at least some level of an interest to sell from property owners. Though you haven't been able to close on one yet, have you been following up with the leads after your initial conversations? For example, someone calls in and you chat with them to find that they may not be interested in selling right then at your price for whatever reason, however over the next several months their motivation may change so a follow-up system should most certainly be in place to touch base with them again and again.
On top of that, be sure you are finding 'why' they called in the first place because your main goal should be to solve their problem before all else as this will inevitably lead to closing deals.