Should I ask for payment upfront from new customers?

The reasoning is not distrust and it helps to frame it that way when asking. A deposit funds the phase where you are working and nothing is visible yet, which is the period during which a project can be abandoned leaving you with unpaid effort. It also establishes that both parties are committed, which changes how the engagement proceeds in ways that are difficult to quantify and obvious in practice.

State it as normal practice rather than as a condition, because how it is presented determines the reaction. A sentence in your proposal saying work begins on receipt of the deposit, followed by the schedule, reads as process. The same request raised separately after somebody has agreed reads as a concern about them specifically, and that is a different conversation.

The amount should cover what you would lose if the project stopped after the first phase. For most service work that is somewhere between a quarter and a half depending on how front loaded the effort is. Stating the reasoning rather than a percentage tends to make the conversation straightforward, since a figure tied to something specific is easier to accept than one that appears conventional.

For anything longer, stage the remaining payments against milestones rather than dates. Money moving when work completes protects both parties: you are not funding months of effort, and the client is not paying for progress that has not happened. It also surfaces disagreements about scope while they are small rather than at the final invoice.

Smaller jobs can frequently be handled by payment on completion, before delivery rather than after. For work where the output is a file or an access credential, that arrangement is simple and removes the collection question entirely. It is worth stating upfront rather than raising at the end.

If a deposit is genuinely a problem for a client, treat that as information rather than an obstacle. Sometimes cash is tight and a smaller first stage solves it. Sometimes they have been let down before and want to see something first, which a reduced initial phase addresses. And occasionally it means they are not in a position to commit at all, which is considerably better to establish before the work than after.

Be consistent, because inconsistency is what creates awkwardness. A business that takes deposits from everybody has a policy. One that decides case by case has a judgement about each client, and clients talk to each other.

Then make paying it trivially easy, with a link rather than bank details and a clear amount. A deposit that requires somebody to arrange a transfer at the moment they decided to proceed introduces friction at exactly the wrong point, and the delay is frequently where enthusiasm cools.

Confirm receipt of the deposit in writing along with the start date, because the transition from agreement to work beginning is where clients most often feel uncertain. A short message acknowledging the payment and stating what happens next converts a bank transfer into a commencement.

Treat the deposit as earned only when the work is done rather than as available cash, since it is money against an obligation you have not yet met. Holding it separately, or at minimum knowing how much of your balance is unearned, prevents the situation where a strong month was actually prepayment and the work still has to be delivered.