Accept the invitation, confirm when to arrive and ask whether there's anything your host would like you to bring. For a first Diwali visit, those answers will help more than a fixed list of gifts and colors.
You could send a message such as: “Thank you for inviting me. Is there anything I should know about clothes or arriving for a particular part of the evening? I'd be happy to bring something if that would help.” Adapt it to how you normally speak to the person.
Get the setting clear before choosing clothes
Find out whether you're going to a home, a community venue or a place of worship. Ask about the dress expected for that gathering. You don't have to buy an unfamiliar outfit simply because you're attending Diwali; if your host suggests a kurta, ask for help with the garment and fit.
For clothes you own, try a shirt and trousers you feel comfortable in, then decide whether you'd enjoy adding color or a wrist accessory. A plain outfit can also be a deliberate choice. A general festival palette won't tell you what suits every family.
If you plan to wear a bracelet, check it with the actual sleeves. Remove it if it presses or catches. Our bracelet style guides give ordinary outfit options without assigning a religious meaning to the piece.
A venue can have specific visitor requirements. For example, Neasden Temple's published guidance asks visitors to remove footwear in its Haveli complex and prohibits indoor photography. That is guidance for that venue, not a description of every private home. Read the instructions for wherever you're going and ask where to put shoes or belongings on arrival.
Bring what is welcome
Ask before choosing food or drink. If the host suggests sweets, check what the household would enjoy and any ingredient restrictions you need to consider. Keep the box's ingredient information with it. If nothing is needed, you can arrive with a greeting and thank your host without bringing another object.
For a household you don't know well, don't guess about alcohol, leather gifts or religious objects. Nor do you need to copy a family gift exchange you've seen elsewhere. A visit doesn't oblige you to buy a personal present for each person there.
If you want to give a close friend something separately, make that its own decision. The gift guides help you choose for the person, not the festival.
Follow the invitation through the evening
Ask whether a particular arrival time matters. If prayer is part of the gathering and you're unsure what participation involves, ask what guests are invited to do. You can explain a personal boundary politely. Don't assume that you should join, stand in a particular place or handle an object without being invited.
Check before taking photographs, especially during worship or of other guests. Put your phone away if asked. If you can't eat something offered, explain politely and ask whether an alternative is available.
Where candles or oil lamps are present, keep loose clothes and hands away from flames. London Fire Brigade's candle guidance specifically includes diya lamps. For fireworks or an outdoor display, follow the host's arrangements, not what other guests are doing.
Afterwards, send a thank-you in your own words. A short message about something you enjoyed is enough.