GMail promotions tab - help me to get into Main tab

Hello, I run E-Mail campaigns from Aweber to Casino Lists (SOI) to mainly subscribers in Canada and Australia. The days my openrate goes down and down. I tried to find out myself what to do via Glocks App but I do not really understand what to do. I see that for Gmail (and many of my subscribers use Gmail) the mails get into the "promotions" tab. I tried to write more personal and not to use to much spammy words but the open rate goes not up. I need an expert showing me what to do and to get out of the "promotions" tab and help me to get better sending performance in general in the future. My list is just small now (around 2100 subscribers) but growing month by month so it would be great to find someone helping me long term also.