If you are not going to assemble this fresh cylinder right away you should coat the cast iron sleeve with oil and put the cylinder in a plastic bag to prevent RUST.
You need to wash the cylinder in HOT water and a good degreaser like TIDE or a liquid like DAWN soap. Immediately after cleaning cylinder you should have a can of WD40 or similar spray handy to put on the CAST IRON liner. It will RUST right before your eyes once it is clean. If you have the luxury of an air compressor, blow the cylinder dry. Respray CAST IRON with WD40, then put it in a plastic bag, or something like that, to keep clean.
Assemble the new piston rings and test fit the wrist pin for snug finger push in fit. Put one circlip in one pin grove right now. Put a clean rag around the rod area to prevent falling things (like other circlip) from falling into cases. Coat the wrist pin bearing with a few drops of your 2-cycle oil. Also put a few drops on the wrist pin surface of the piston, before sliding the pin into the piston. Install the other pin circlip and be sure both clips are seated in groves and not bent.
Remove the rag and install the cylinder base gasket onto the CLEAN dry cases. Make sure area is 'old gasket free' and has no gouges or nicks that could cause an air leak. Blow the cylinder off once again and using your 2-STROKE oil lightly coat the sleeve around the bottom part of liner. The oil will be pushed on up by the piston as you slide the cylinder onto piston. This way you can hold the cylinder at the top with Clean Dry Hands and finish the job knowing you didn't contaminate the sleeve or the piston with dirt. If the cylinder has cylinder base mounting nuts install and torque them now. Install the head gasket, cylinder head and head mounting nuts or bolts. Torque to mfg. specifications in factory suggested criss cross pattern See your engine manual, you did buy the factory manual didn't you?
Double check everything as you go so you don't forget anything. ENJOY your your new found H.P., have a great day.