Congrats on your first purchase. A home with a guest house is an excellent way to get started in the rental world. I've been a LL for 12 years and self manage all my doors. Here are a few of my "tips" but remember, there is so much more than what is below...
Education - You can never get enough of it. You are now legally responsible for someone now. And if you screw it up you can be fined thousands of dollars. Here are some good sites to use
Biggerpockets.com - it is an amazing site, get immersed in it. This is where i go if i have specific questions. I just posted one today and it was answered in less than 20 minutes.
Rentprep.com - a new site i've found, no fluff, gets right to the point.
Jasonhartman.com - he's a turnkey provider, but his podcasts have a lot of excellent information. I skip a lot of his intro's now and just dive into the content.
Rent Collection - The way i collect the rent is I have them deposit it into a bank account i set up. I usually choose the closest bank to the property. But if you are literally living next door, just have them drop the check off at your place. I have considered doing an online collection service. Cozy.com has a pretty good setup for this, but they hold onto your money for longer than i want to wait. If i get a few more units, i may look into something like this. You can pay them a nominal amount to get the money released earlier.
Screening - this is the most important thing you can do here. Go to Biggerpockets.com, download one of their free Applications. I already had a lease so i didn't look at theirs but i'm sure they have some good ones in there. I meet with every potential tenant, you can learn a lot by just talking to them. I also always check out the interior of their car. If its a mess, chances are they will keep their home just as messy. One thing I used to do was sign the contracts at their homes. I haven't done that for years though... Obviously, you can't discriminate, so if you are rejecting an applicant you need to have a valid reason why. I write that reason down on the application and keep it for years in my reject folder. I also say no pets and no smoking. But there is a market for pets, I'm amazed at how many calls i get saying will i accept a pet. I've been burned before so i'm not ready to change my stance yet.
What i require is a completed application, let them provide me their credit report from freecreditreport.com, and a copy of their latest pay stubs. Then check their references. Cozy also has applications and background reporting which the tenant pays for. Again its pretty slick, but my system has worked for me for over a decade.
As stated before, there's a lot more to it than this, good luck.