Advice from Retin-A/Tretinoin users please!

[BadlyDrawnBuoy]

Hi, I've been using 0.025% Tretinoin for a few months, building up usage gradually up to 3 times per week. I'm using it for any-ageing (in my mid-40s). All going well but I have a few questions and would appreciate advice from seasoned users:

1. Should I aim to eventually be using it nightly? If not what's the optimal number of times per week?
2. Do I stay on 0.025% or move up to 0.5% when I finish the tube of 0.025%? If I move to the stronger stuff should I go back to starting it once a week and gradually build up again?
3. I'm going on holiday to a very hot climate in August. I'll continue to wear 50 SPF daily - is it ok to keep applying the 0.0.25% Retin a at night on hols?
4. Any recommendations for an effective AHA toner to get rid of occasional flakiness? I've been using Clarins exfoliating toner a couple of times each week - working well but it's bit pricey so a cheaper but effective alternative would be great! Also any recommendations for a good cheaper facial SPF - I'm using dermalogica which is great but ££.

Thanks for any advice you can share!

Hopeful bump

I've been using it for around 2 years now and I use the 0.05%.
1 yes I think you should try to use tretinoin every night to get maximal benefit. I use it all over my face, right up to my lower eyelashes under my eyes.
2 I would start to use the 0.05% when you have finished your current tube. You might find a bit of peeling with a higher strength so I would perhaps use it 3x weekly for a month, every second night for a month then try to use every day thereafter. I don't think you need to go any higher than 0.05% as the wrinkle reducing effects are not associated with increased irritation. The 0.1% almost made my face fall of! I can't use it at all.
3 I don't see why you can't use it while you are on holiday. Women all over the world use it, especially in very hot areas of America for example so I think as long as your face is well protected and you wear a sun hat etc it should be fine.
4 I like Nip and Fab toning pads. The glycolic ones are good (I also use the salicylic acid ones as I have oily skin) and they don't cost much. They always seem to be on offer in boots or SD. Sunscreen-I use a Korean one. Biore watery essence spf 50 which suits my skin well as I have oily skin and this product is nice and light. Costs around £7 on Amazon and has fab reviews.

Where do you buy the retin-a from?

Pharmacy Geoff online following lots of recommendations on MN.

Thanks for your advice Wellhello - v helpful!