@Chadrick Bailey  Also use a separate credit card for the expenses related to the property even though you can track with a piece of software it is easier to keep track if you don't mix expenses. 

I know the Appfolio sales team, as well as Juniper Square, and all the other investor portals try to talk up how they are a CRM, but they simply are not.Salesforce is your most powerful CRM, and likely overkill for 99% of situationsHubspot is a great option, and depending on contact list size is fairly affordableGoHighLevel is another one that is becoming more popular, but I have never used directly.There are a ton out there, and I am biased to Hubspot, because it is the one I have the most experience with, but the general contact record tracking, customization, ability to build dashboards, etc are all great in Hubspot and adequate to track contacts that may fall into various buckets: i.e. you can build your broker lists, your investor lists, your tenant lists, track your calls to each, setup up custom email campaigns for each separately, etc.

When I was an agent I would often track properties that I considered to be "MLS gems" properties that where in need of an update or serious repairs. 

I’m determined to get back on track by hiring a new licensed architect to update plans, resolve the permit issue, and lift the stop work orders.

I have found that MyFico.com is a pretty solid tool for tracking/evaluating personal FICO info.

I was using Zimplemoney to track 3-4 owner finance loans (not handle payments or escrow), the last 8 years, and last week they went up from $36/year to $23-47 per month. 

Quote from @David Robertson: For rehabbing, I think the most tedious and time-consuming part of expense tracking is itemizing receipts from places like Home Depot or Lowe's.

When I started flipping, I found it way too easy to lose track of receipts, go over budget, or forget who I paid and when.

Even if I am able to track down the next of kin how would I know if they are authorized to sell the property?

This may be  a long shot, but would love to perhaps partner with, work out a deal with someone that does flips in my area.