I done many weekend trips with rear seat bag +/- panier's; like many good suggestions previous;
what I've found helps
pack 2-3 days before hand; remove all contents and look at it; and ask youself what is necessary? and just take whats necessary; your ride will be more enjoyable with less stuff to keep tract of and weight you down. Lighter = more fun on the bike and easier to control. Then if possible pack evething and set it on the bike; it will take a while the first time and adjust straps so nothing rubs (especially on moving parts or hot exhaust)
Double check that all zippers are closed; straps and clips are connected and covers are tight. (you'll be surprised
)
I prefer panier's due to lower center of gravity and have a saddle bag thst goes over the seat; on top of the panniers if I have alot of stuff; and you have to keep an eye on stuff if its parked unfortunatly; so park in busy spots;
also like to lay on the tank on long straight stretches with no traffic around; try it you'll love it; monsters were made to be more arrowdynamic;
beware of being upright; windy and high speed corners; your front end gets light and you can drift. (monster problem); lean forward and get weight over the front wheel in these conditions.
stop; take breaks and lots of photos expeciaslly at scenic spots.
lightweight nylon rain pants and coat are nice along with shin high waterproof boots and extra gloves... plan for it to rain (here north of NW on BC Can.
If its dry I find I get dry throat and sinuses combined with exaust / dust; so a small bottle of water helps used at every stop but not too much then your stopping to pee befor the next break ... see at breaks tahe a leak.
... all seems obvious; but you'd be surprised.
oh ya; also check fluids ( break & oil)and tire air pressure after the bikes loaded befor you go 2-4 lbs extra tire pressure is good for extra weight; bring and use a tire pressure gauge.
On longer rides I find I get sore in funny places; neck;wrists if Im leaning on the handle bars too much and or sore back or sometimes cramps in calf /hamstrings/ outer hips (hip flexor muscle?) o; you'll notice more on day 2 and after when you sit on the bike; asides from being saddle sore
Enjoy; ride on.