I could understand a STAR or DP if you were flying far away or to another busy airport. McKinney to Marshall doesn't seem like that kind of situation.
In the D/FW area, arrivals come over four VORs--the one to the Northeast is Bonham (probably the Fingr three arrival). However, looking at STARs in the U.S. Terminal procedures, I don't see one listed arriving from the NE coming to McKinney. They seem to be more concerned bringing you from one of the other directions and working you in through D/FW arrival traffic.
Departure procedures go cardnal directions. Looks like Garland Two or DallasEight go east. Hubbard Five is a possiblity. Look at each one and note the transition closest to your intended direction. Remember, these are just in case you lose commo. You should get radar vectors to the airway.
If you're real concerned, put each one where you copy your clearance with the first transition that looks likely. When they read it, you can just circle the correct one.
I recently left Hobby at night and didn't know what they'd give me. Look for the ones going in the general direction you will head to join the airway. Normally, even as busy as it is here, there are only one or two choices in your direction.
Clearances will get easier as you copy more of them. I have a check list that I fill in before calling.
A recent clearance I received was like this:
Cleared to: C47
Initial Heading: Runway heading
Vectors? Vectors to DP
Routing: As filed or direct. If an airway; write the route in before calling
Initial Altitude:
Final Altitude:
Squawk:
Transponder:
Have the charts open to your route and the DP marked or open to the page you think you'll get.
I've called from a hand held in the cockpit when concerned about a clearance after doing everything to depart except cranking the engine. On one occassion, it really helped me clear up an issue I didn't understand. On another, I didn't start the engine; departure delays were lengthy!
Dave