UK Standard Visitor Visa: How to mail multiple applications when applying as a family

Should I send both applications in same envelope? Maybe, put each application in small envelope and then put both applications in a bigger envelope?

This is a great question. The best strategy is to treat both applications at 'arms length' when you send them. The reason for this is that the mail room procedures for witnessing and logging evidence is done for one applicant at a time.

Should I put my financial documents (Bank statements , Pay Slips) in both applications(i.e. mine and my wife's)?

Another great question. Both applications should have the spouse's GWF number written large and plainly visible in the remarks section. Include the financials in your application and your wife's remarks should point out that she is relying upon your evidence. You are (hopefully) submitting originals.

You need to read the guidance! Here's what it says...

If you are applying as a family/group you do not need to provide multiple copies of the same documents.

If they think you haven't read the guidance (which you have NOT), the application will be scrutinized more carefully (that's a bad thing).

I have an old passport which is expired. Is there any need to send this passport as well with my application?

What evidential value does your old passport have? It's not required and if you do send it you should explain why you are submitting it and why you want them to look at it.

After receiving stamped passport ,I can safely outline the steps that I followed :-

1.) There is no need to send visa application papers separately. You can have them in the same envelope without any partition. Just have them sorted and don't mix them up.

2.) You need to send all passports - even expired passports.

3.)If you buy priority service, then receipts need to be on top of application papers. Also , on outside of envelope , mention "Priority service" in large letters.

4.) Do not use Fedex to send or return post.