If your bike is starting okay,... adjusting the decompression lever isn't really necessary...
Valve adjustment is pretty easy,... I figure a 1 to 1 1/2 hour job, taking it easy....
first time may be a little longer... You do have to remove the seat and tank...
Gas tank is tricky with the stock petcock... wiggle, wiggle...
How To: Adjust your Valves
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1255580802