Decent domains cost money and although they do not have a picture of Benjamin Franklin sitting on them usually, they should be cared for as if they did.
One thing that a lot of Internet marketers fail to do properly is to keep their PBN (private blog network sites) properly organized and updated and that can cost a lot of money for not only the owner of the sites but also any sites that you are targeting.
What I have done is prepare an Excel file that is free to download that one can use to manage their private blog network sites as to what domain they are targeting, the registrar and registration dates, their host and host IP's as well as any updates done both on and off-site for the PBN sites themselves as well as the target site you are trying to rank.
There was a time when I would feel very comfortable using a private blog site inside my network for a variety of targeted sites I was trying to rank. I would link from one private blog network site to a number of different sites I was working on ranking.
That ship has sailed though as I've done a bunch of testing and have found that if I am able to target just one site I want to rank with each private blog network site, the domain I'm targeting has better results in the search engine rankings. I'm not saying that you cannot use a private blog network site for more than one target URL but I don't think that is the highest and best use for that private blog network site and if you are looking to get highest and best use you want to use that site for only one domain.
I'm also a fan of hosting companies such as Hostnine, where, with a reseller account that runs just a few hundred dollars a year, you are able to have multiple IP's inside your account with each site having its own cPanel so that it appears as if they are all hosted in different places. Sure, with a service such as that, you're going to have the same name servers but I have not found that to be an issue at this point in time as the different IP addresses give you the benefit needed for what is considered an individual property in the eyes of the search engines.
Feel free to download this Excel file at no cost to you; I think if you don't have a way to manage your private blog network sites this will work for you as a template.
By way of explanation if you look at the template itself you'll see the red tab is a master PBN list and what that would be is a list of each and every private blog site that you own as a master list. Your Domain url, the person/site where you acquired your domain, what you paid, your registrar and the registrar renewal date, as well as the host and the host renewal, and of course, the IP address on which the site is hosted all have columns there.
The second tab, which is blue, has your target domain. Your target domain is the domain that you are trying to rank and has your url, the date the domain was originated, the registrar, the registration renewal date, the host as well as the renewal date there, the hosting IP address and a spot to date when you did any recent onsite or offsite activity. If the target domain is not yours, but a clients, some of that information may be helpful as a bonus to remind your client when they need to pay their renewal fees.
The rust colored tabs that are named PBN 1, PBN 2, etc are your PBN domains which are supporting, or back linking, the targeted domain. Those are set so that you can update when there has been some activity that relates to your target domain.
There are columns for any onsite updates you make, the URL that relates to those updates as well as the action that was done if it was a page added, content added to a page, images added or whatever you are doing to build the actual PBN site up as well as corresponding columns for the off site activity that you may do to maintain your PBN site are all there for you.
You can add as many targeted domains as required, as well as adding as many supporting domains to the right of them, in your spreadsheet. Doing so will keep everything in one place so that if you add or take away from your private blog network properties you can easily update your spreadsheet to keep abreast of the online real estate that you own. If you have a myriad of properties this can get to be a decent sized spread sheet for your PBN network(s) and should make life a little easier for you if you are not using something like this for the properties you own and manage.
One more thing... be sure to save your file EVERY time you update it or you will be using words that a sailor uses on a regular basis.