Flightplan

Reach an LKO at 75-80 Km and decouple the Mainstage (park in orbit preparing for reentry*)
Burn Escape Orbit and leave the Kerbin System (Mun Swing By isn´t required)
Configure your Transfer Orbit to Jool (standard Hohmann Transfer)
Use Orbital mechanics to create Orbit around Jool and reach Laythe(with Tylo, similar how to see at my pics)
Your Destination Orbit around Laythe shoud be at ~60 Km with more than 3000 m/s Delta V (will be doubled after Landing on Laythe!)
Decouple the Lander from the Return-Module and use please max 100 m/s to deorbit (for precission landing on a Island, I recommend the Mod Trajectories, Landing on Water also possible)
Use Parachutes to slow down your speed and land with maximum 4 m/s! (Over ~7 m/s Landing Legs can be destroy) Perform and collect your Science stuff
Plan your Rendezvous to Return Modul and burn back into Orbit. Please perform an sharp Gravity Turn, so that you achieve an Altitude at ~55 Km (at the best you used the first Stage from the Lander for this)
After you hopefully succesful docking Maneuver you can drive back to Kerbin OR you plan you next Maneuver to reach Pol! Before this, please transfer the Oxidizer into the Lander (Doughnut Tanks between Heatshield and Fairing Plate, recommended for experienced pilots)
Your Destination Orbit around Pol shoud be at ~30 Km with more than 4000 m/s Delta V (sounds much, but you use this for a safe travel back to Kerbin, if you don´t want to perform difficulty Maneuvers!)
Use maybe 50-70 m/s to deorbit and land on Pol, repeat the stuff like Laythe and travel back to Return-Modul
To Travel back to Kerbin and create an Escape Orbit, use Tylo again (I leaved Pol before this)
Leave Jool and create the Rendezvous with Kerbin. In my Test i was fly very inefficent and arrived Kerbin with ~2160 DV, before Orbit Burn.
Normally you have a rest fuel in the Lander that can be used for deorbit, so you can park the Return Module around Kerbin to use for other Missions (Maybe as Transfer Stage or something) If not, you must use the R-Module for deorbit.

*Mainstage landing (Brings 400.000 Funds back)

Deorbit with 400 m/s or more (try to land on solid ground)
If you to fast during descent, reduce speed to avoid overheat
Use the Parachutes (AG 9,0)
Land with max 4 m/s

Big White Rocket - Laythe Return [Stock]