It sounds like you conquered the first step in real estate which is figuring out how much time you have to offer to your new business. If you only have 15 hours per week, you will drive yourself crazy trying to cram 30 hours worth of work into that time slot. Once you figure out how many hours you have, you will now need to sit down to figure out how to allocate that amount of time. I sent out several thousand pieces of mail one month when I was working my wholesaling business "part time" and didn't have enough time to actually follow up with any of the leads. It drove me crazy! It seems like a good problem but it's not. You won't get any deals when you're overwhelmed.
If you have under 15 hours of real estate time each week, I'd recommend sending out a micro mailing campaign (under 25 pieces per week.. maybe hand written?) or to call FSBO's. The good thing about calling FSBO's is that you have much more control over when you can make or receive a call. If you have a busy work week with your current job, call less FSBO's... if you have a light work week, maybe make more calls. You won't run into the problem of not having enough time in the week to follow up. I understand cold calling sucks and you will get rejected many times but it will also teaches you how to make offers over the phone which is a valuable asset for any investor. Treat your investing career as a long term process and working FSBO's is a great skill set to learn which can build on in the future.
Here a few good ways to get leads:
1. PropertyRadar- It's $60 per month but you can download 10k(15K?) leads per month into excel to mail. You can essentially create your own list with your own criteria and then start mailing to the tax address. This website has other features but take a look, it could help you.
2. US Leads List- Lance and Terry have an inherited (probate,estate,etc) where you can purchase a list of inherited properties broken down by county. Call them to make sure your county is available. I'll let them go over pricing with you.
3. Title/Escrow company- Get to know a title company in your area because you will need a good one when you start wholesaling properties. They can get you an absentee out of state or out of county list which many investors live by when they send out mailings. Ours doesn't break down the addresses by equity but they're super cheap so we've mailed this many times!
5. Bird Dogs- Post adds on craigslist for property finders. Target mailmen, pizza delivery guys, uber or taxi drivers, etc. Mainly your looking for people that want to make some extra money. Pay them 10% commission of a closed wholesale deal. Have them drive through neighborhoods and look for distressed and/or vacant properties and send them to your email. Then mail to the tax address and wait for call backs.
Some of these may have legal issues in your area so do your due diligence if you decide to go forward with any of the lists above!