Pineapple Guava Germination:
"Seeds are Very Tiny, more like the size of Black Pepper than an Actual seed, so use a pair of Tweezers to handle them."
1) Prepare a seed-flat with soil-less seed-starting mix. Pineapple guava seeds are prone to soil microbes that exist in garden soil and soil-based potting soil. A soil-less seed starting mix provides a sterile environment, increasing germination rates.
2) Use a mix of equal parts sand, perlite and peat moss or coconut coir to provide an environment that combines good drainage, a loose medium and a support system for the new seedlings. 
3) Use a heated propagator to keep soil temperature above 75 degrees F.
4) Like any Tropical or Exotic seed, Pineapple guava seeds take 21 to 60 days to germinate at 75+ degrees F.