Thanks MG here's a little more to ponder..
A lot thought goes into handicapping, and not enough about wagering. If you stretch your thought processes a little, working on your wagering is very much like working on your handicapping. I've tried to explain a little in the past re my methods, So I thought I would show a simplified idea that pretty much anybody could use, as long as they have some ability to study ROI on various wagers. That might come from database research.

The basic idea is this. First, you study wagering a little bit, and find some basic ideas that ARE NOT PROFITABLE. That means, they have a VERY negative ROI. The WORSE the strategies, the better. Make a list of these "rules" for betting methods or techniques that NOBODY SHOULD USE.

Then, you handicap the races, I use a Monte Carlo simulator. You can get servicable software like this for free on the Internet, so there's no reason why this can't be easily done. You use this software to produce a ranked list of trifecta wagers, with the most likely outcomes at the top, and the least likely at the bottom.

Then you simply go through the list of ranked wagers, eliminating all of the BAD BETS that you identified in step one. This is a simple concept, and only requires a modest investment of effort (time) and some thinking. But it's a MUCH more effective way of structuring your wagers than relying on the old 3-dog box, or the 23/234/2345, or the 1/2345.

Let's look at a simulated example to get the feeling for how this works. Let's say I'm handicapping a nice little race, and I can assume the crowd favorite will be the #1 dog, and the crowd's basic ranking order is this: 14537682. You can pretty much get this off the Tote board, or spend a few minutes "thinking like the crowd" and do it yourself. You don't need specific odds, just the crowd rankings. For most purposes, it doesn't even have to be particularly accurate past identifying the crowd favorite.

Now from those wagering studies you did, here are the bets to avoid. The left side is the description of the wager, and the bets on the right are the actual box numbers the rules generate for the current race we are working.

Wager Elimination Rules

From "Box" players inefficiency... these are the parts of three-dog and four-dog boxes that really are bad investments. Rankings based on crowd odds.

1. 234/1/234 = -31% ROI (345/1/345)
2. 234/234/1 = -43% ROI (345/345/1)

From "Standouts" players inefficiency... the key players overbet the favorite with the best three or four dogs. Rankings based on crowd odds.

3. 1/2345/2345 = -36% ROI (1/3457/3457)

From "Numbers" players inefficiency... people overbet certain boxes, no matter what kind of dog is in them. These are the problem boxes we find from a simple post position study.

4. Box the 123 boxes = -36% ROI (123/123/123)
5. Box the 128 boxes = -31% ROI (128/128/128)
6. Box the 178 boxes = -34% ROI (178/178/178)
7. Box the 678 boxes = -36% ROI (678/678/678)

From "Hot Dogs etc formguides" players. Buy your formguides, and avoid their plays. Or avoid the any tipsters selections

8. Hot Dog = 1-4-7 (147/147/147)
9. The Recorder = 4-3-6 (346/346/346)

From "Factors" players. If you can study factors, you'll find that the crowd overplays some of them. At this track, they SEVERELY overplay the dogs with the best 6-line finish average in the guide. (In my example, the #1 has the best 6-line finish average, followed by the #2 and the #3. Easily calculated from the program page.)

10. 6-line Finish Avg 1/23/23 (1/37/37)
11. 6-line Finish Avg 1/2/ALL (1/3/245678)

Well, those 11 rules are a pretty good start. Here is an example of the simulation results for this race. Here are the simple win percentages as predicted by the simulator, just for your reference:

Sim Results:Box Win Percentages
4 29.2%
1 26.8%
5 10.8%
3 10.5%
7 6.2%
6 5.7%
8 5.6%
2 5.3%

And here are the top 50 Ranked Trifecta Wagers. Note that to the right side of the wagers, I have noted the rule from above that triggered to ELIMINATE this straight trifecta from use for this race. Thus you would want to play the "naked" wagers, the ones left after your eliminations. Here are the first 50 wagers from the simulator, their probabilities, and the trigger rules...

1. 1-4-5 2.08% Rule 3
2. 1-4-3 1.99% Rule 3
3. 4-1-3 1.85% Rule 1
4. 4-1-5 1.85% Rule 1
5. 1-3-4 1.44% Rule 3
6. 4-5-1 1.41% Rule 2
7. 1-5-4 1.41% Rule 3
8. 4-3-1 1.35% Rule 2
9. 1-4-7 1.33% Rule 3
10. 1-4-6 1.30%
11. 4-1-7 1.22% Rule 8
12. 1-4-8 1.17%
13. 4-1-8 1.15%
14. 4-1-2 1.12%
15. 1-4-2 1.12%
16. 4-1-6 1.09%
17. 4-3-5 1.01%
18. 5-4-1 0.94% Rule 2
19. 4-5-3 0.92%
20. 5-1-4 0.86% Rule 1

Hope this gives you some more areas of study