In regards to the A50 negotiations?
Well, it's a bit of a minefield so I'm not sure how much detail I'll be able to give you, but I'll outline some of my concerns and agreements with the approach taken by Theresa May.
Firstly, I would be a lot more concilitary in tone towards the EU (as May seems to be doing a lot more of now). It's undermining our position in these negotiations when Hammond threats to turn London into a tax haven for multi-national corporations.
I would also have sought a greater mandate from devolved administrations. She hasn't really got a UK wide consensus, and probably shoudl've been a bit more accepting to the concerns and demands of the Scottish Parliament (Also towards Welsh farming, who will more than likely be recked by Brexit).
As for the actual negotiations, I agree she should guarantee the rights of EU citizens straight away. I'm pretty sure this will happen, but it would have be a good touch if Theresa May had guaranteed this prior to negotiations.
I also think she shouldn't have said that we will leave the ECJ, this severely limits our access to the single market and creates a dilema as to where rulings will be made on our future trading relationship. I also think we should accept preferential migration from the EU into the UK,probably in the form of early advertising to EU citizens for jobs before they are advertised globally. This would probably show sufficient give and take to get a beter deal.
Also, and perhaps rather cynicially of me. We must use everything to our advantage in these negotiations whilst remaining civic. There will clearly be disagreements between the EU27 as they seek to defend their industries and secutiry ties, we should probably aim to use this to our advantage as much as we can.
With all that said, this is a monumental challenge for our nation. Certianly this a lose-lose situation for the UK and the EU,and no doubt come two years time we will have a considerably worse deal out of the EU than we currently have now.