What to do with extra house that's paid for.

[Thomas Smircic]

Hi all. I'm new to real estate investing but we have an extra small 400 sf house on 1/5 acre of land in a residential area of St Petersburg Florida which we are currently renting way to cheap at 500/mo to a family member on a fixed income. We bought it for 45k and have seen its current value at between130-160k. Our credit isn't to good right now (below 600) due to some now resolved health issues and missed payments on debts. We both have good jobs and collectively bring in around 130k/year. I also have some construction experience and have a friend who is a GC. I had planned on creating more equity by trying to build the house myself by getting some architectural plans and then subbing out the work when the cost of materials and labor comes down a bit more. The other options would be to try and take the equity and leverage it to buy another property(s) or just sell it outright and then reinvest the money in more real estate.  Interest rates are going up and the housing market may decline. Given all the scenarios, what would be the best move now? Any advice would be appreciated, thanks!