From Tsim Sha Tsui to Ocean Park, you can take MTR to Admiralty Station and then take BUs 629.
To Disneyland, you can take MTR to Disneyland Station, take Tsuen Wan Line to Lai King Station and then change to Tung Chung Line, finally change to Disney Resort Line at Sunny Bay Station.
It might cost you around HKD20 per person for each trip.
You can also go to the Peak, Stanley Market, Avenue of Stars, Temple Street Night Market, Ladies Market, etc.