Although it isn't certain that a CAD Tech will do a survey (some go their whole careers without doing 1), it is quite common to need to occassionally.
With this being the first survey you are doing, I would suggest getting a set of drawing from another survey and check out what information is on there, then also check against a few other drawings.
The key is to dimension EVERYTHING. It is always better to dimension something that you don't need, rather than not dimensioning something that you do need. And always check your dimensions, try and tally it up as you are going along, and if it doesn't seem right then dimension again.
Things that always seem to be missing are meter points, window/door heights, wall types, eaves height, the landscape, site levels, floor to ceiling height, etc.
I assume that if you are doing this on your own then you will be using a disto-meter rather than a measuring tape? If not, then I would suggest asking your boss if they can get 1 as you will find it a lot easier.
Also, don't worry about the time. Take as long as you need. Again, it is better that you get the survey right in 5 hours, rather than get it wrong it 2.
Most importantly, have fun. Remember, it may be tedious, but it is a day out of the office...
Hope this helps.