I don't mean to come across as trying to tell you what to do. I'm just giving you suggestions.
Here's how I'd run this if I had the venue:
The first week it'd be a straight up smashfest. People can come free and play free. Then, if the people want a singles tourney, then give them a singles tourney ($5 entry, $5 pot). I assume that the venue is a store/arcade? If it is, then even if you let them in free, you're doing the store justice by attracting new customers.
The next week, people can still come in free and play, but they know that a tourney's going down. So make sure that you set a time for signups (If you open the doors to Smashers at 12, I'd say start signups for dubz at 1-2, and have the tourney start at 2 30($5 entrance, $10 per team to pot)). So the tourney ended woohoo! Give yourself like an hour to play, and then announce that singles signups will be starting up, and give the signups an hour. ($5 entrance, $5 pot) After the deadline, give late people a half hour to show up, and then start the tourney. After the tourney's over, everybody can chill out and play for as long as you have the venue, and that's it.
Nobody really wants to pay $5 for friendlies. If they want to play in tourney, that's when you ask for the $5 entrance. My first tourney, I had about fifteen or twenty people show up for singles. I had like two months or so for planning. And, I was fairly new to smashboards at the time. You've had two tournies, on thursdays, and had a pretty decent attendance. Trust me. If you keep this up, it'll get bigger. Plus, if you get somebody's attention, that person might tell their friend, who might tell their friend, and your tournies will get pretty big.