Hi Rebecca,
You are correct that different brands work differently. Indica is believed to be more calming and helps me sleep. Sativa is believed to be more uplifting. And a lot of edibles contain a hybrid (mix) of the two. Another factor is when you last had a meal. I find the effects more noticeable if I eat it on an empty stomach. If I eat a big meal and then have an edible I hardly notice anything. I like to buy chocolate bars because I can cut it into the size I want, usually 5 or 10 mg. It takes about an hour before I feel the effects, so an hour before bedtime works for me. Also, never drive while under the effects because it definitely changes your reaction time.