Hands with two 5+ card suits are not difficult to bid if you are able to open the bidding . But if your opponent opens in front of you it is useful to have bids that will tell your partner what you have
The high card strength will vary and judgement must be used in relation to vulnerability and it is essential in any regular partnership to have an agreement about this.
The overcall should never be less than a 7 loser and analysis shows that most “good” overcalls are usually 6 losers or better
There are many conventions available

All have advantages and drawbacks- I think the two below are are the easiest to remember.
Others that are quite common are Ghestam, Copenhagen- CRO (Colour-Rank-Odd) and Wenble.
The problem with these is that they all incorporate bids that can seem ambiguous. For example if the opponents open 1 ♥ a bid of 3 ♣ from Partner means Diamonds and Spades and its very easy in casual partnerships to forget and respond to a natural jump overcall.
All are probably as effective as any other in practiced partnerships.

As with any Convention,if playing with a casual partner, make sure you are both playing the same.

This is how I understand the following Conventions and I am fairly sure this is the most common way of playing them, but there are ”Modified‘versions around so, again, be careful

Michaels Cue Bids
The system is as follows -:
Cue of a Minor shows both Majors
Cue of Major shows the other Major and an unspecified Minor - 2NT from Responder asks for the Minor
2NT over anything shows the lowest two unbid suits
3 ♣ over 1 ♣ shows Spades and Diamonds (i.e. not the Majors and not both red suits which would have been shown by 2NT)
3♦ over 1 ♦ shows Spades and Clubs (i.e. not the Majors and not Hearts and Clubs which would have been shown by 2NT)

Quantum
The system is as follows -:
2NT over anything shows the lowest two unbid suits
2 ♣ over 1 ♣ shows Spades and Diamonds as 2NT would show the red suits or the two lowest unbid suits.
And similarly 2 ♦ over 1 ♦ shows Spades and Clubs
Cue of a Minor at the three level shows both Majors
Cue of Major shows the other Major and an unspecified Minor - 2NT from responder asks for the Minor

In either system a ”wrong“ suit reply by partner shows good six card suit of their own and no better than singleton in your Major. After 1 ♥ -2 ♥ (showing Spades and a Minor) a bid of 3 ♦ or 3♣ by Responder would show a 6 card suit and no better than a singleton Spade

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