Stew,
You received lots of good tips and encouragement so far. I have a few thoughts on the subject as well.
I'm 55+ and also travel solo most of the time. However, lately I've been combining a RS tour with an equal amount of solo travel and that's been fantastic so far.
One of the most enjoyable aspects of travel for me is the complete freedom to go where I want and see those sites that are of most interest to me, without having to worry about anyone else. Solo travel provides that, but I can also day tour with others if desired.
Regarding the alcohol, everyone handles this a bit differently. I've found that I can have a glass or two of wine early in the flight, but after that I limit myself to the occasional coffee and of course lots of water (I always buy a bottle of water in the departure area to supplement that provided on the flight).
I've also experienced many comments from friends, family and co-workers on travelling solo, and received many puzzled looks from other people after they've asked why I'm alone. The impression I've often had is that they feel that anyone that actually chooses to travel alone "must have something wrong with them". I tend to ignore these comments, and refuse to allow others to dictate which travel method is best for me.
I tend to mix Hostel stays with budget Hotels (often those listed in Rick's books), as I like a few nights of privacy once in a while. I've found that it's easy to meet people in the smaller Hotels as well (especially at breakfast time).
I think it's normal to have a few "pre-trip jitters" before a trip. That happens to me as well. I sometimes begin to doubt whether I really want to go on the trip. However when departure day comes and I'm seated on the plane, the adventure begins and the apprehension disappears!
I carry a Cell Phone so that I can maintain contact with family, mostly via text messages (quite inexpensive).
Hope you have a great time on your trip!