The tips are so bland that they're not even helpful to new players. For me, they also disappear before the images of players appear so I rarely have time to read them fully.
I would suggest that you make them contextual based on the champions selected, and individual for each player, also invite higher tier players to write them.
* Don't let Darius get 6 stacks on you! Go for shorter trades
* Kaitlyn's ultimate can be body blocked
* Blitzcranks Q takes 20-10 seconds to cooldown based on level
* Place control wards to spot Evelyn
* Every third auto attack, Vayne deals bonus true damage based on your maximum health
You could choose which tip to show based on likely lane opponent or whichever champion in the pool of opponents that has had the most success against you. This helps all players to increase their game knowledge which is essential when you consider you've got 137 champions to learn to play around as a new player.
More generic advice might be more relevant to bronze players:
* 2 waves of minions are worth more then a kill
* minions will block your path, be careful
* run into a bush to drop minion aggro, early-mid game, they deal substatial damage to all champions
* Press Tab to see when baron, dragon and other buffs will spawn
* ping cooldowns to announce them to your team, also works in the tab screen
You could take this further, if you're playing a marksmen and the enemy team has characters like Swain, Warwick or Trundle, then place a tip suggesting they buy an Executioners Calling.