After all your hard training, how do you treat your rest days? This is something I've been working on a lot more heavily recently. Treat the catabolic portion of your training with the same respect you treat the anabolic portion with. Put the same energy and focus into your recovery that you put into your training. First and foremost make sure you are getting proper nutrition and sleep. Everything I'm going to cover follows those 2 things. This means making sure you're eating enough proteins/complex carbs/fats, it also means making sure you don't have a vitamin or mineral deficiency.
Stretching is an important part of recovery. It's important to stretch when you're warm, not cold. This means stretching should not be the first thing you do in the gym. I save my stretching for the end of the workout, I'll also stretch between sets. After a warm-up is also a fine time to stretch. Stretching should be considered an important part of your strength training. When tendons and ligaments are broken down through training they heal tighter and with less elasticity. This means a decrease in range of motion. To prevent this stretching after your workout will aide in restoring that range of motion. If your goal is to be more flexible, it would be best to do multiple static and dynamic stretching sessions a day.
SOFT TISSUE MASSAGE
I am a big advocate for massage, not everyone is. At one point in my life I was training hard, eating a lot and growing. Without much focus on recovery, usually what happens is over-training and then hitting a "wall". Luckily I wasn't to that point yet, but I had a friend who was a massage therapist. She told me that I should really start getting regular massages to help my muscles heal. Reluctantly, I said fine whatever lets try it. The very next day all my lifts felt immediately stronger. I was blown away, and have since always programed massage therapy into my recovery.
There is lots of information on foam rolling online. Ironically my girlfriend loved foam rolling; I got her a foam roller for Christmas, and I fell in love with it as well. In the same manner that massages work, foam rolling is a great release for tight/sore muscles. This can be added immediately following your workout, on your rest days, or both. Typically with tightness or contraction, blood isn't flowing to the muscle efficiently, which is an important part of recovery. I will say foam rolling has done wonders for me, in releasing tight overworked muscles.
I saved the best for last here, and am about to get into the real "meat and potatoes" of recovery. When you're injured, lets say you cut your finger. Your body will send red blood cells to the area to form a blood clot and begin the healing process. The healing process for muscles works in a similar way. However, for muscles you can stimulate the red blood cells yourself. Active recovery is the single most efficient way to recover from hard training, and may seem completely backwards for some. Old school powerlifters after an intense day of training would go back in the very next day and hit the same muscle groups at a very low weight. Why? To Recover! Mobility work/ Active recovery is working the muscles at low resistance through the full range of motion. This can be done with a variety of exercises, but anything that works the muscle through a full range of motion is ideal. If you've ever been seriously injured, a physical therapist will follow a similar protocol. If you're knee is bad they aren't just gonna put you in a bed and say hopefully in 6 months you can walk again. They're gonna have you working the affected area with low resistance, this may mean in a swimming pool or assisted walking; but the idea is the same you want to move red blood cells to the area for recovery.
Unfortunately, I do not know enough about acupuncture or chiropractic work to comment on them. I will say I have seen a chiropractor a few times, and will continue to get an adjustment once every few months to make sure my body is moving efficiently.
Things to avoid?
Not moving when you're sore. Anti-Inflammatory drugs inhibit muscle growth. Icing, as it slows down the blood in the area, and is the opposite of what we want.