Hey guys, im kinda new to this cc churning process and dont know where to start and i would really appreciate some help. my biggest concern is that i sign up for a cc and then find out later that i could have gotten a way better deal if i waited.

so here is what im working with
i have a credit score of around 780
i usually spend about 1000-1200 a month and just signed up for bluebird so i guess i can up my spending to include rent to about 1800
i travel about 3 times a year
i dont stay at high end hotels like hilton, starwoods, or hyatt
i want to get about 2-3 cards every 3-6 months
the credit cards i have are chase freedom, united mileage plus select, and miles by discover.

so what cards should i go for that are currently available?
i also got an offer for 50k delta after spending $1000, which im thinking of doing. is it possible to apply for the business card also and get the additional 50k by doing the 2 browser trick?
thanks for any help in advance