Not risky as such I wouldn't say, just that they'd take a bit of experimentation to make them work as you'd like. If you're not a confident flier if might be good to recruit the help of someone who is to do the test flying for you?

It's a case of getting the size and positioning right. On fullsize the designers wouls usually not include them in a design, but if upon test flying there were concerns about unsatisfactory handling at or near the stall, then the design engineers will have the required data to calculate how big a strip is needed and exactly where to put it for the desired effect. If they're present on fullsize aircraft, they are almost certainly the result of some sort of rectification or corrective work to address the handling. If you study photos of the fullsize F4U Corsairs, you'll see that some got a small stall strip on the leading edge of one wing only - the reason being that this aircraft had a tendancy to roll the other way during final stages of landing due to assymetric slip stream encountered from the prop. The little strip on the wing which rose stalled a small section of it, compensating for the roll. Definately not something the designers originally had in mind - just a correction to make the aircraft safer. The same usually goes even when they're symmetrical on aircraft - if during test flying the a/c tends to drop a wing at the stall, it may well get stall strips to see what happens. If that cures it, they get included on the production line

We don't have the luxury of data, so we need to do it by trial and error instead.

Your model shouldn't become significantly less predictable if you get it wrong - they just might not work as you hoped... experimentation would settle this one way or another