I agree with horse manure...I grew my peppers on a bed that had 10 year old composted horse manure and in Mexico, it old donkey manure. Peppers like the ground loose. I had one corner of my pepper bed in Wyoming where the soil had been very compacted. It was previously a stallions pen and he stood in that corner all the time (best view of potential females...
) No matter what I did the pepper plants in that corner were never as large and the peppers sucked...I finally just quit putting any there.
I started all my peppers in Wyoming in February. Some varieties take much longer to germinate so you loose days that way.
Peppers need the most careful application of "hardening off". Too much sun or wind the first week and the leaves just disappear (I had green sticks one year after a 30 mph wind...they just never recovered.) I always pinched blossom upon transplant because you want the root system to take hold..time for fruit later.
Chose varieties that are suitable to your area...I have wasted more time and effort planting tempermental or totally different zone varieties than I care to admit. Without A LOT of effort, 120 day maturing hot peppers that came from Trinidad were not going to thrive in Wyoming's average 90 day growing season and bizarro weather without constant fussing and cossetting. I finally decided it was not worth it. It's all about maximizing your time, financial investment, space and effort and... swear to the heavens that is really the truth of it. Pride stubbornness are a couple (among several) of my most egregious faults.
Typically, large "non bell" peppers (like giant Marconi or several of the other Marconis) are much easier to grow and ripen than typical Bell Peppers. For Bells, hybrids are probably the safest bet. I grew 68 kinds of peppers this last season in Mexico and I had a terrific year. (I was trialing some...and I am a maniac...) I grew very few "typical" bell peppers.