To be honest, I've gotten to where I can see amber trichs without a microscope at all....They give off a gorgeous hue on dried cured flowers.
Fresh flowers can be harder to judge for sure though...If you follow brimck's advice, make sure to take multiple samples, from multiple parts of the plant.
I ordered a 45x jewlers loupe the other day and just now placed an order for a 60x loupe. Got paranoid maybe the 45 wasnt strong enough lol, and for $3 a pop and free shipping, cant complain !!
Try pulling a little bit off than sitting it on a stable surface, I know moving around slightly with a microscope/loupe can be a bitch.