First off, nothing wrong with using those positions as your starting lineup. (Not sure whether that was part of the question...

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As far as strategy goes, it depends a lot on whether you also get to draft a bench, make waiver pickups between games, and so on. In most formats, you're stuck with the players you draft, so the key is obviously to project the way the playoff games will turn out as accurately as possible. (Yeah Arlo, tell me something I didn't know...

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Anyway, there are two main schools of thought about draft strategy. Many drafters will try to project each available player's point totals and draft based on positional scarcity (which can shift a bit in playoff formats - waiting until round 7 to draft a QB might not be such a great idea), the same as in a regular-season league. The other common plan is to pick up as many players as you can from one team and hope to ride that team to the title. That's risky, particularly since you probably can't pick a team like the Colts where several players might be off the board before you even have a chance to call out a name, but it can be brilliant if it works.
Of course there are also lots of hybrids, like picking up a QB-WR combo that you think can go deep into the playoffs and drafting the rest of your roster by scarcity. One thing to be careful about in your format is the RBs. If you have a large amount of drafters and some will be taking two RBs, the position might dry up quickly...
Good luck, and have a blast!
