Some of the things I've done to practice include:
1) Get to know my discs, especially a new one, by playing an entire round with it. You can do this by just carrying the disc if it is a mid-range or a putter. If a driver, you can just throw it off every tee, or if you don't want to "sacrifice the round" you can throw it as a second shot off the tees.
2) Go to the football field. I use this to work on my max distance and to get to know the distances on my discs. Sometimes I take surveying flags and recreate holes at local courses that I'm having trouble with (must go left of this flag and right of that one for instance.) I also empty my bag throwing all anhyzer throws, pick them up and empty it throwing all hyzer throws. Then I throw into the wind trying to determine how much hyzer to put on each disc to throw it straight (hyzer-flip) and then throw with the wind at my back trying to figure out which discs work for a flex shot and how much anhyzer I have to put on them. You can then throw with a right to left crosswind and a left to right cross wind. If you're trying to learn a forehand or a tomahawk or whatever, start at the football field. Plus, you put a lot less wear on your discs doing this than smacking into trees at the course.
3) Putt. Perfect Putt 360 is nice. But I've come up with a handful of other games to work on other aspects of my putting. Such as how to go for it from 50 feet without leaving too big of a come-back putt. You can attach a score to any game you want. PP360 talks about a "pro version". Well, I made a Barney version. The distances are 10, 12.5, 15, 17.5, and 20 and I throw 5 from each spot. Very quick and helps me eliminate embarrassing misses. 20 footers are becoming gimmees for me.
4) When I'm alone I throw multiple discs. Sometimes 4 or 5 off the tee and then I just keep track of my score playing the first one. Usually I'm trying to hit several different lines. I might throw an unstable driver on an anhyzer line, a stable one on a hyzer line, a fairway driver as a worm burner, and a "roc down the middle." Or I'll try to throw a bunch of discs on the same line. You quickly learn which lines at a course and which discs are high-percentage for you and which are not. If I really blow an approach or a putt I might throw a second one too. I might stop at a really unique basket (downhill putt, or straddle putt, or a basket on a hill) in the middle of the round and throw 10 or 20 putts at it. I play a lot during the day on weekdays and rarely have someone come through when I'm doing this.
5) I try to play with other people I don't know when I can get them to let me join their group. They don't know it, but I'm pretending I'm in a tournament with them. Helps you deal with tournament pressure. If they're pretty good, I also often learn some new lines or other techniques. If nothing else, they inspire me to practice more.
6) I make up object courses at local parks. New lines. New distances. A lot easier than traveling out of the local area to new courses. Plus I can go to the park around the corner, play 18, and be back in an hour. I've got a half hour drive to my nearest real course. Plus, this way I can throw my discs into ponds, which my local park has but none of the local courses do.