My Wedding is next week but Ill share somethings I've learnt from my planning
1) I work in SG but my wedding is in KL, due to this I have to fly back and forth to do my wedding plans and that total money would have probably been enough for me to hire a wedding planner instead. So I would suggest if so happen you are doing a wedding in a different country, DIY might not be a very wise option (unless you take a very long leave)
2) Set a comfortable / affordable budget, but always allow room for minor payments you may miss on the way (flowers, wedding car, ang pao, GST, additional guests, travelling expenses, hotel room, make up artist, wedding performers)
3) The mind set of a DIY wedding planning should always be a fun activity rather than a stressful chore. Always support each other and work together.
4) With so many types and cuts of diamond in the market, its easy to get lost and confused. Depending on who are you pleasing in the future, a bigger diamond with an average clarity and average cut may be appreciated better compared to a smaller diamond with excellent clarity and excellent cut. Could be even cheaper too.
5) If you travel a lot you can save on beverage expenses by buying duty free and collecting them (provided if the restaurant allows)
6) Ask your wife to nego with mum in law to give you back a bigger portion of the dowry

(in my case I got back almost 50%)
Just my 2 cents!