I like to keep things simple !
I mainly look at handicaps and at the following .........
class movement - obviously dropping in class preferred, this related to handicap marks
trip - D win or some reason why a horse might improve for a new trip
going
track configuration (particularly uphill finishes, straight/bend)
I look at the last 3 as a combined factor trip/track/going ......... will the horse be effective at this trip on this track on today's going
that's mainly it
I will check trainer form to see if the yard is horribly out of form or banging winners in left, right and centre
and draw if the trip/track/going favours one side
Days since run I might look at to see how a horse goes after a break (this combined with trainer form)
these last few things mainly to see if there's any reason to abandon a selection I've made by looking at class and trip/track/going