Brett Davies
Remove all of the old sealant, every little bit, doing this can be time consuming and monotonous, they do sell silicone remover which makes the job a little easier (£5 -£10 from most DIY suppliers, you will also require methylated spirit, ghe instructions will explain how to use), making the new seal look good may be difficult for a beginner (takes a lot of practice) the main concern is that the silicone sticks to the bath and tiles, before applying the new seal, fill the bath with cold water ( this positions the bath at its lowest, making the silicone seal last longer) make sure the area to be sealed is completely clean and dry, then apply the new seal, leave to set for at leasr 24 hours. Good luck Brett