If you are gonna spend real money just dont do normal or increased priority 10+1 gacha unless ur waifu is in it. Its for poor freemiums like me, even i wont do 10+1 anymore unless it gives a free gold like it did past weeks.
If you decide to spend, spend your 50$ on 11-pull+guaranteed rainbow deals. Best value for your money)
60$ step-ups are iffier, but it is still 1 6* and 1-2 5*...