Since you re a NEWBIE,,,lots of things to consider
first being budget,,,do you want luxury line or regular? For instance,I ve tried the luxury ,,like Regent and LOVE it.All inclusive,,,tips,all restaurants,excursions,liquor,,etc.....and you DO get top notch food as you mentioned.Also, smoking only in very limited areas..Do check bottom of main page for list of smoking policies on various ships..
Second,figure WHERE you want to go,,,or at least first one,,ex..if Western ,check out each port site on google for tourism,,or look at you tube to get some idea if this is what you want.Same for Eastern,,etc.
Third,read lots of reviews of each line and visit their website to see all details of ship,room,food,etc.
Can make a spread sheet and add up ALL the charges,,tips,drinks package,shore trips,etc.to determine EXACTLY what it ll cost..
Then give it a try,,,have fun,,and can always change mind on NEXT ONE>..good luck.