I bought one of the "Mustang" took kits from Walmart when we first bought our TT. Hammer, pliers, screwdrivers, various sockets, wire cutters, wire connectors, zip ties, etc. Comes in a folding plastic case that keeps everything neat and clean. Not too heavy at all, keep it in a back storage area.
The tool I use most often out of it is the neat little 6" level!
I also made sure to include a socket that fits the lugs on the trailer, as of course they are a different size than the ones on my truck. For a jack, I found that my truck's jack works fine on my trailer if I have to change a tire.