The general guidelines for visiting the UK are that:
- you can demonstrate strong ties to your normal country of residence (the IO must be satisfied that you will leave the UK at the end of your trip and won't attempt to overstay your visitor visa)
- you have sufficient finances and accommodation for the duration of your trip (travel/medical insurance is also helpful to show you can cover any medical expenses that may arise)
- you spend as much time in the UK as outside the UK (essentially, that you are not trying to live in the UK with a succession of visitor visas; if you spend 3 months in the UK, it is advised to spend 3 months outside the UK and so on)
If you can demonstrate these things with evidence (ex. being able to show the IO your return travel ticket(s), bank balances, hotel reservations, etc), you are unlikely to have any issues visiting the UK, especially if you space out your visits so that you're spending equal amounts of time inside and outside the UK.
I should note that you have previous adverse UK immigration history (ex. refused visa, bounce, etc), it is highly recommended to apply for a visitor visa in advance of travel.