Selena Gomez has very beautiful hair I think I agree with you there, it would be lovely to have hair like hers. Is there any medical reason why your hair is very fine? I would suggest before you have extensions you see your GP to check that you are not on any medication that is affecting the growth and strength of your own hair. The best method for your own hair would be the Micro ring method. It is an adhesive and chemical free method that does not use heat to apply nor chemicals to remove. It is a tiny nickel ring that is looped onto your own hair and the hair extension bond is slipped threw the loop this is clamped shut and trimmed down. You must ensure that this is fitted by a qualified professional. As for the growth of your own hair I would recommend taking some vitamin B complex, drinking lots of water, eat well and try to stay away from the straighteners, curlers, and any harsh hair products such as colours, perms, and even harsh shampoos. This will all make a big difference. Hope this has helped!