Pretty good advice there from Alejandro, you can also buy shoulder straps that attach to the tripod, prefer it to a bag myself
If they don’t already come with anything on the legs, bit of pipe lagging makes them much nicer to the hand in the colder weather
Three extension legs will be more stable then the four variety and if you don’t need the full height use the larger legs out first. Legs are either twist lock or clip type, much prefer the latter, but opinions are divided on that choice
Don’t forget you will also need a head, ball or 3 way type and again a matter of opinion although in my view a good solid ball head takes some beating. Make sure it has a Q/R plate too, so much easier to attach and detach the camera, friction control is another handy feature to have