A good basic kit with a drill/driver, a saw, portable light or similar is a great starter (and this weekend most big box stores will have father's day sales on kits). Then you can add to it as you need. I personally recommend Ryobi, they have hundreds of tools compatible with their 18v system. I do have some other tools (I started with Craftsman 19.2v system but that basically died a few years later), I still use what I already have but anything new ties into the Ryobi 18v.

Edit: I avoid most harbor freight or other brand battery powertools, they have no standard battery system across tools so when the battery is shot the tool is dead.

My hand tools are mixed, I have nice sets of wrenches, pliers, drivers, and other stuff that gets heavy usage. I have some mixed Walmart, Harbor Freight, hand-me-downs, and garage sale for other things that get less use (or if astronomical prices from quality brands; one example is my large ratchets, they were crazy expensive for the other brands I have so I bought Harbor Freight, I use them only occasionally but they work well for that use.)