BAPP until you reach £10k for the 2for1 voucher then onto Amex Gold for random extra points for no real reason (can still give referrals for both cards), I once got 8MR per £1 spent at a hotel!!! I would have been back more often but it was Gleneagles....
If your friend has a lot of spare time then go for 3v cards if already earning the wages you state he might not find it worthwhile. You buy 3v pre paid visa cards using your Amex, you can then use them in places that don't accept Amex or you can deposit them into a NS&I Direct Saver account, transfer out to your normal bank account and then pay off your Amex bill fee free. If you bought them in Tesco you will receive Clubcard points + bonus points that can then be converted to Avios.
Tell him to read
Head for Points
Tesco Mastercard for those places that don't take Amex, can convert the Clubcard points to Virgin Adlantic or BA Avios.
Same here, have been looking to get back into points collecting, really should have done it sooner but have been a bit busy settling in. Have applied for a Amex but was refused due to being self employed and being here less than 2 years, even though I stated my UK Amex numbers in the application. Reading more into it I think Westpac Altitude Black will be more suitable and will be handy to pay off my approx 100k tax/gst bill when it comes in