I struggled with transfer switch’s and interlock kits in my last few houses. Adding a transfer switch is expensive and limiting in the number of circuits you can move over. Interlock switches work well, if your code and existing panel support them. My current house has 400 amp service, so getting all my critical circuits under generator power wasn’t possible without serious rewiring ($$$$). Here is an easier way. GenerLink switch. Comes in 30 and 40 amp versions. Simple and safe. Best of all, you can take it with you when you move. I can’t post a link as I’m still under the min post count. Home Depot sells them. The 30 amp runs $650.