when I text should the first letter be uppercase or lowercase?
If you are starting a sentence and not in a hurry always use the upper case for first letter. It makes people feel that you took the time to properly address them.
When you text,the first letter should be uppercase. (in my opinion)
If it's a sentence or compete question, or a proper noun.....a capital.
Uppercase. Then it doesn't trip you up when Grammar and stuff like that actually matters