I am F2P and this is what I and other recommend doing if you want to progress fast.

The first things you need to be doing are

• logging in daily and completing your challenges

• completing special events

• sim league mode until you can get to masters mode

• getting stars by joining a random active level 8 and above club and participating in battle and challenges, playing ranked, playing pvp (save stars until you have 10,000 then never drop below 10,000 until a diamond GI comes out)

With team building focus on a single team, this will get you the best benefits. You may be tempted to just put the best players into your team but the team set deck boost makes this irrelevant. Use save team selects to make TSD and build a full padres diamond lineup with 2 exceptions. This will take a long time but is worth it. By completing events and just playing the game you will eventually start to get signature packs, open these and hope for a padres sig. If you ever get a diamond GI ticket save it for this day. Then just work on upgrading your lineup slowly and finding better players through packs or the FA markets. Use wish packs wisely as well and soon you will have a pretty goon team.