Betting ? for the board

[wac]

First off i am not very good at playing pk 3 4 so i usually bet one race at a time and on some races im willing to bet $50 per race which is a good size bet to me but i wonder if im not allocating my money in the best way. Usually i find a horse that is at decent odds 10-1 or higher say he is horse 1 my bets look like this:
20w10p 1
2ex 2,3,4,5/1
1tri 2,3,4,5/2,3,4,5/1
my question is that should i be betting less win place and try to put the 1 on top of some of these ex tri bets? its just that i am not right very often and when i am i want to cream the race. should it look more like this?
10w5p1=15
2ex 2,3,4,5/1then 1/2,3,4,5=16
1tri 2,3,4,5/2,3,4,5/1 then 1/2345/2345=24
that takes me to 55 and i guess i would want a 2345/1/2345=12 now we are at $67. I really dont know which is the best way to do it and it gets aggravating when my "1" wins and i get the win place which is great but man id sure like to get some signers and need some help. im pretty new at this so this may seem like a stupid ? but forgive me for my lack of knowledge. thanks