In my opinion is the only one who can tell you what to do....yourself
It is always nice to give free Readings and as long as they don't expel other task, and you feel confident in doing it...then it will be a great gift to those who receive.
Many times when we give away such "free gift" the demand increase and this way other task will suffer....then you have two choices... start to pick those you want to respond to..which will lead to some will feel you are unfair..or start with paid Readings, which will decrease the demand...but as you said..give more time to do each reading and by that give a higher quality on the product.
The main thing is that you feel confident that you "sell" something that has a value, but I am sure you will find many Readers the take fees, which they never should have done
A Reading are a prediction of Events seen from the situation today.
Since we all have free will, the querent has to work active to fulfill the Reading or to avoid it.
Since much are up to the Seeker...there can never be delivered any guaranties that a reading will be fulfilled.... but there should at least be possible to see that the Reader are into what the Querent are paying for.
Most Readers give the reservation that all readings are only given for entertainment purpose....and this I think is a good rule.
If a Reader don't gives any good Predictions...the word will travel fast...and he/she might get less to do...and if he/she is good, the opposite will occur
Here on the site are you and other welcome to give free readings
Good luck!