Occasionally when you have runners on-base, extra advanced strategy options will appear while batting. Using them out at the correct moments can be very useful. Their availability is dependent on your players and the situation. You can also enter your team menu and choose "Gameplay" to adjust how frequently these opportunities will be presented.
Batting
Wait for the best pitch before swinging. Watch the pitcher and note when he winds up. Allow him pitch and watch the ball's trajectory carefully. Lay off on pitches that are not right. As long as you do not swing and the ball is thrown at enough of an awkward angle, it will be a ball.
Trades
When low on gold you can get new players by trading. Enter the "Trades" menu to offer up three players in exchange for a new player. The players obtained from trades are usually in the 3+ star range. To make a successful trade, you must first acquire the offer players. Tap on each one to see where you can get them.
Upgrades
Upgrading permanently increases a specific stat for your entire team. They are expensive, but worth the expense if you will not be spending elsewhere. Each individual upgrade is small, but can add up with future upgrades.